A series that focused on the victims and community impact of the Columbine High School shootings. Originally published in the Rocky Mountain News (Denver, CO) in 1999.

Inside the Columbine Investigation

They were determined to do it right. Now, the law enforcement professionals investigating a terrible tragedy are finishing their work. This is the story of what they did -- and the toll it took on them.

Jefferson County District Attorney Dave Thomas, pictured in his office last month, had the heartbreaking task of telling a parent that his 14-year-old had been killed at Columbine. The case took an emotional toll on Thomas and many other involved in the investigation.

Dave Thomas didn't want to wait.

It was Wednesday, April 21, 1999 -- 24 hours after gunshots and explosions pierced the quiet of a spring day at Columbine High School.

Now, Jefferson County's district attorney held a list of 13 names -- a teacher and 12 students who hadn't come home the night before.

The teacher and the kids, Thomas knew in his heart, were dead.

Many of their families, filled with dread, had gathered at Leawood Elementary School, a quarter-mile from Columbine, waiting for their awful fears to be confirmed.

It would take another day for the coroner to formally identify the bodies.

But Thomas, 51, a graying man whose sad green eyes had seen tragedy in the courtroom and in his own life, couldn't bear to prolong their agony. So he drove to Leawood and walked inside.

There, he encountered Bob Curnow, whose son Steven was on the list.

"I don't know how to tell you this," Thomas began.

"You don't have to," Curnow replied. "It's written on your face."

Later, Thomas phoned Ray Kechter, an investigator in his own office. Kechter's grandson, 16-year-old Matt, was on the list, too.

As they talked, Thomas made his friend a promise.

Then, numb with grief, he returned to Columbine to get his first look inside the school.

Don't touch anything, investigators warned him.

In the library, where 12 died, he found the body of Cassie Bernall, facedown on the floor. Her hair looked so clean and shiny.

Then he saw Matt Kechter, his body intertwined with Isaiah Shoels' under a table near the windows.

He knelt quietly, carefully, and, as he'd promised a broken-hearted grandfather, Dave Thomas began to speak.

It's OK, Matt, he said softly. Everything's going to be OK. Your family will make it. They'll find a way to move on. Please don't worry about them. Everything's going to be all right.

He hoped Matt could hear him.

In the days, weeks and months to come, a task force of more than 100 detectives from a dozen local, state and federal law enforcement agencies would mount the biggest criminal investigation in Colorado history.

They would use sophisticated computers to track thousands of tips and pieces of evidence and enhance bits of grainy videotape. They would conduct 4,500 interviews with students, teachers, parents and others -- anyone who had been at Columbine that day, anyone who knew Eric Harris and Dylan Klebold, the two killers.

They would forge an unprecedented bond of teamwork among traditionally turf-conscious police agencies.

And they would struggle, sometimes in vain, to hold back a flood tide of emotion.

They would try, fighting through anger and bafflement, to answer the biggest question of all: What drove these boys to hate so much?

Now, almost eight months after the worst school shooting in U.S. history, Jefferson County sheriff's officials are poised to release their final report on the events of April 20.

This is the story of that investigation.

Sheriff's Lt. John Kiekbusch stands in a room containing 300 binders filled with reports from Columbine investigators. Kiekbusch is directing the criminal probe of the high school tragedy, an exhaustive inquiry nearing its completion.

For Jefferson County Sheriff's Lt. John Kiekbusch, it began as a typical Tuesday morning.

A crack homicide investigator for the Jefferson County Sheriff's Department, Kiekbusch was in the midst of a tedious meeting with a federal grants writer.

Then a deputy stuck his head in the door.

Turn on the radio, he said. There's been some kind of school shooting.

Kiekbusch nodded. Sure. A bad joke.

But the moment he flipped on the radio, he froze:

"Possible shots fired at Columbine High School."

Minutes later, Kiekbusch gunned his squad car out of the parking lot at the sheriff's headquarters in Golden and roared across Sixth Avenue, the gas pedal punched to the floor. As the car lurched, the siren mysteriously quit. Then the flashing red lights cut out.

A tiny fuse, deep beneath the dash, had blown.

Kiekbusch's radio crackled with emergency calls as other vehicles raced toward Columbine, a proud suburban high school with almost 2,000 students.

Speeding along without lights or sirens, a frustrated Kiekbusch alternately rode the brake and jammed the gas, surging helter-skelter through traffic in his unmarked squad car.

Back at headquarters, detective Kate Battan returned from an early lunch to find a crime-scene van idling at the curb.

Something's up, she told herself, hurrying toward the investigators' offices on the second floor.

"Where is everyone?" she asked.

She found them in a conference room, crowded around a color television suspended from the ceiling. The first broadcasts from the school flickered across the screen.

Two minutes later, she was back in her car, alone, on a drive that would take her on an unfathomable descent into horror.

As the investigators sped out of the Jefferson County government complex near Golden, Dave Thomas stood in his nearby office, away from the windows, reviewing paperwork. He didn't see the detectives' cars tearing by.

Soon he was riveted to his own TV -- a small, two-dial, black-and-white set on his windowsill.

Students fleeing Columbine were claiming that a senior named Eric Harris was one of the gunmen.

Kathy Sasak, one of Thomas' top prosecutors, turned to a computer at his desk and ran a search on Harris' name.

"He's in the system," she said.

On the screen was a 1998 court file detailing the boy's arrest for breaking into a van and documenting his trip through juvenile courts into a pre-trial diversion program.

Thomas scribbled notes on Eric David Harris -- 18 years old, 5-foot-9, 140 pounds, brown hair, green eyes, born April 9, 1981, his Social Security number. As he looked for more information, up popped the name of Harris' co-defendant in that case: Dylan Bennet Klebold, 17.

Thomas grabbed assistant DA Mark Pautler and hurried to the parking lot downstairs. Together they sped toward Columbine 14 miles away, carrying a legal pad full of notes on the potential suspects.

As Battan screeched to a halt outside Columbine, she encountered more police cars than you'd see at a cop's funeral.

By early afternoon, 615 officers from 27 agencies had converged on the school. Kids kept pouring from the doors, hands on their heads, and running for their lives toward Clement and Leawood parks and into nearby neighborhoods.

A SWAT team moves through a neighborhood near Columbine High School on April 20. Soon after the first reports of shooting, 615 officers from 27 law enforcement agencies rushed to the scene.

Investigators stopped every student and teacher they could to ask them what they had seen -- and whether the gunmen might have slipped out the door in the crowd.

Thomas and Pautler worked their way through the confusion, finally finding Sheriff's Sgt. Randy West, a seasoned investigator and supervisor, at a temporary command post in Clement Park. Thomas thrust the notes on Harris and Klebold into his hands.

But Lt. Dave Walcher, marshaling the massive initial response to the shooting, was already holding a list of five potential suspects. Harris and Klebold were 1 and 2.

"That's literally how far behind the incident the investigation was running," Walcher says. "Twenty minutes, no more."

The last gunshots -- the ones signaling the death of the two gunmen -- had not yet been fired. But already the investigation was in high gear, unfolding in multiple directions.

As students fled Columbine, they encountered not only detectives but journalists. Often hysterical, the kids blurted what they believed they had seen. In those first, frenzied minutes, myths about Harris and Klebold began to form -- and flash around the world.

Some students said Harris and Klebold always dressed in black, like Goths.

Some described them as computer geniuses, Hitler fanatics and members of a mysterious organization, the "Trench Coat Mafia."

Investigators would spend months chasing those myths, only to debunk most of them.

When he heard the news on the 18th floor of the Denver Federal Building downtown, FBI supervisor Dwayne Fuselier, head of the regional domestic terrorism unit, had more on his mind than a hostage situation at Columbine. His son Brian was a student there.

Fuselier was the first FBI supervisor on the scene. In a shirt and tie, he stood out among the crowd of uniformed officers. With him was Sgt. Don Estep, a Jefferson County sheriff's deputy on special assignment with the FBI. Estep quickly found Jefferson County Sheriff John Stone and undersheriff John Dunaway and introduced them to Fuselier.

Minutes later, in a squad car, Estep brought Fuselier and John Kiekbusch together.

Fuselier soon would be named to a command team to oversee the investigation -- and to bring in badly needed federal resources.

He spent much of the first afternoon inside an Arapahoe County sheriff's van talking on his cell phone to students barricaded in the school. With him were two other seasoned FBI hostage negotiators.

One of them, Mark Holstlaw, had been at home, just a quarter-mile from the school, when the call came. He'd had a tooth pulled that morning, and he was holding an ice pack to his jaw.

"I didn't think I would be much good as a negotiator with a mouth full of cotton, but I went anyway," he recalls.

Using extension numbers supplied by school officials, the negotiators talked with students in the administration area, the choir room and elsewhere.

As they dialed, Fuselier, wondering where his son was, spoke with his wife, Mimi.

Do you know where Brian is? she asked.

He told her he believed their boy was at the public library across Clement Park from the school. But he wasn't sure.

"I didn't tell her that I knew then that we had students who had been killed outside," he says.

At the scene, Kiekbusch and West talked about how to structure the investigation.

West recommended that Battan, 41, be named lead investigator. Her specialty was financial crimes, but she had worked plenty of homicide cases in seven years as a detective.

Her dedication was well-known. In her office, a simple sign reads:

"We speak for the dead."

While Battan and West would coordinate every angle, ultimate command of the investigation would fall to Kiekbusch, 53, a career cop with a sandy mustache, a quick smile and a reputation as a meticulous and sometimes demanding boss.

Stone had known Kiekbusch for three decades -- they'd worked heists together as young detectives in Lakewood.

He was confident his old friend could handle whatever the case would bring.

By 2 p.m., less than three hours after the attack began, Battan, cell phone glued to her ear, had crafted the affidavits she needed to get search warrants for the homes of Harris and Klebold.

Information on Harris and Klebold -- and a growing number of other potential suspects -- was coming in as quickly as investigators could grab her attention.

She scrawled notes, then phoned the information to the sheriff's office, where a secretary typed it up. Battan recited the boilerplate language of an affidavit and fleshed it out with emerging facts.

As she worked, she sent detectives to the Harris and Klebold homes.

Their orders: Kick everyone out, make sure it's safe, secure the scene, wait for the warrants.

Already Battan was thinking: No mistakes. Handle everything as if it will end in a major prosecution.

"Everyone learned a lot from hearing about the O.J. Simpson case and from the JonBenet Ramsey case," she says. "We didn't need another situation like those."

At the same time, Estep and other intelligence officers probed for everything they could learn about Harris, Klebold and others who might have been involved. If they had to negotiate with the gunmen, Estep reasoned, they'd need that information, and fast.

But how many suspects were there?

No one knew.

Shaken students described a dozen characteristics of the gunmen. Someone was shooting from the rooftop. Two gunmen were wearing dark, Western dusters. One killer had a white T-shirt.

Out of the chaos, conflicting stories became the rule. Investigators got the first inkling of how difficult their work would be.

There would be at least 2,000 witnesses to interview -- some who saw nothing, others who knew a lot. Some would be wounded students. Many others would be in shock themselves.

Battan dispatched detectives to every hospital.

She sent them in pursuit of the first wave of evidence -- bloody clothing, bullet fragments, statements from the wounded.

Fuselier had spent hours trying to calm students still inside the school. At 3:30 p.m., his phone rang.

His wife was at Leawood Elementary, where frantic parents had rushed to await word on unaccounted-for children.

Brian's safe, she told him. He's here.

Barely 10 minutes later came a brief radio transmission from a SWAT team working its way through the Columbine library. The words stopped everyone in their tracks.

The bodies of Harris and Klebold were on the library floor, apparent suicides. Around them lay the bodies of 10 students they'd killed there.

Bomb squad trucks are deployed to remove explosives found at Columbine. Investigators found more than 80 bombs in the school and the cars and homes of the killers.

It was 4 p.m., and the enormity of the massacre was just beginning to sink in. West said collecting thousands of pieces of evidence would strain the sheriff's resources.

"What can I do to help?" FBI agent Fuselier asked him.

Thirty minutes later, 18 FBI evidence specialists were headed for Columbine. But before they could begin to dissect the crime scene, they had to solve a major problem.

The two killers had tossed bombs all over the school in their death march. Some appeared to be rigged to injure police officers and rescuers.

It meant investigators couldn't get inside to start assessing the crime scene, to remove bodies or gather evidence, until every explosive had been defused.

Thomas milled about the command post, watching SWAT teams gear up for repeated sweeps through the school.

He saw students and teachers moving through the park. Finally, he approached a group of kids huddled together and sat down on the grass with them.

He offered them his phone so they could call their parents, only to find that the blizzard of cellular traffic made it nearly impossible to get through.

One of the first students he talked to was near hysteria.

"I saw him shoot Rachel Scott," the boy cried. "I saw him. I know she's dead. I saw her go down."

Thomas tried to calm him.

"I said the stupid things to him that you say. 'Everything is going to be OK, it's going to be OK,"' Thomas says. "And you know it isn't going to be OK. It never will be OK again."

As day turned to night, investigators hauled evidence from the homes of Harris and Klebold.

At Harris' house, they found the barrel of a sawed-off shotgun, bomb-making materials and a journal filled with hateful ramblings and threats.

They found videotapes, some showing Harris, Klebold and two friends shooting guns. They confiscated a computer filled with Harris' bitter writings.

In Leawood Elementary's gymnasium, scores of anxious parents milled about, disbelief on their faces. They'd heard the news reports that Sheriff Stone feared the death toll could climb as high as 25. And they hadn't found their kids.

In the early evening, Thomas headed there. So did county coroner Nancy Bodelson.

Thomas climbed onto the stage and began to explain that authorities were trying to get the Columbine kids to Leawood. He told them not to worry.

Then Bodelson took the stage, looking out over a room of distraught parents. She explained her job -- to identify the dead and to learn how their lives ended.

Dealing with traumatized families was nothing new for Bodelson, 48. She'd spent years as an emergency room physician, trying to put broken bodies back together, consoling families when she couldn't.

Now she found herself asking families for information.

She handed out forms asking for the name, age, address, height, weight, clothing and any distinguishing marks of students still unaccounted for.

When she told parents she might need their children's dental records, their faces went pale.

She asked them to note whether their children had driver's licenses in case she needed their fingerprints. She walked out with more forms than she would eventually need to identify the dead.

About 9 p.m., outside Columbine, Sgt. West called his wife.

"Don't send the kids to school tomorrow," he told her.

As night fell, SWAT teams were still going through Columbine room by room. They knew Harris and Klebold were dead, but other gunmen might be hiding inside.

They summoned Thomas Lofland to help.

The master electrician for Jefferson County schools, Lofland knew Columbine's layout from one end to the other. He also could shut down the blaring fire alarm that distracted and frustrated the police inside.

But when Lofland arrived, the officers made it clear it was risky work. Explosives littered the school.

Lofland shrugged off the danger. He would do what he could.

SWAT members gave him a bulletproof vest and helmet.

"I felt terrified," Lofland says. Then a sheriff's captain rejected the idea of taking him inside.

Instead, Lofland recounted every detail he could think of, hiding places such as elevator shafts, maintenance and heating runs -- and ways to get to them.

Then he found a place to sit near the Red Cross tent, adjacent to the command post in Clement Park. From there he watched.

SWAT teams kept coming out of the school for debriefings. He could see the pain on their faces.

"Some of them were in tears," he says. "It was very emotional to see, these guys in their combat gear. They were very affected."

Shortly before 10:30 p.m., bomb technicians cleared a path to the administration area, where control panels for the electrical system were located. A single officer escorted Lofland and another electrician inside, telling them to follow close behind.

"We were seeing shell casings on the floor and bullet holes in the walls," Lofland says. "A television set in the administration area had been shattered, the teachers' mailboxes had been knocked over, and live rounds and casings were on the floor."

They quickly found the main power source for the fire alarm and cut it.

An eerie silence fell over the school, broken only by the steady spray of indoor sprinklers that had flooded the floors. Strobe lights used as a fire alarm for the deaf continued to flash -- and would for another three weeks. Lofland cut off water to the sprinklers.

Outside, as officers thanked the two electricians for their help, a powerful explosion ripped the night air.

A chill went down Lofland's back. There was no doubt about the sound -- it was a bomb.

The device, recovered inside the school, had detonated as it was being loaded into a bomb trailer.

Nobody was hurt. But the incident frayed what nerves the bomb technicians had left, and it pushed commanders to make a quick decision.

People were exhausted. Someone might get hurt.

They sent everyone home to rest, posted security at the perimeter and agreed to regroup at 6:30 Wednesday morning.

Moments earlier, agent Marcus Motte of the federal Bureau of Alcohol, Tobacco and Firearms had gone inside the school with bomb technicians. He was peering into the flooded cafeteria, looking at hundreds of backpacks left behind 11 hours earlier by panicked students. Some floated in the water covering the floor. Others sat on top of tables.

The instant the fire alarm went dead, Motte heard a strange, almost surreal sound welling up faintly from inside, like birds chirping.

Across the cafeteria, telephone pagers in the abandoned backpacks were going off, unanswered calls from desperate parents.

Where are you? Please, please call home.

As Kate Battan stepped through the shattered doors of Columbine High School at 7:30 Wednesday morning, she could hear only one sound: the pounding of her heart.

Everything else was silent, enveloped in unearthly quiet.

Battan moved carefully past broken glass and shell casings and into the school. West, Bodelson and Chris Andrist, supervisor of the sheriff's crime laboratory, walked beside her.

Bodelson had awakened early. She spent time reassuring her two teen-agers, both students at Wheat Ridge High School, that everything would be OK.

You don't need to worry, she told them. You're at a good school.

"Mom," her daughter replied, "Columbine's just like Wheat Ridge."

Now Bodelson was at Columbine, where bullet holes pocked the walls and the acrid odor of black powder lingered in the air.

The four investigators moved to the entrance of the library. They carried notepads, a Polaroid camera and sheets of paper with descriptions of missing students.

The SWAT teams and paramedics who had looked inside the library had told them it was bad. Now they were going to see how bad it really was.

The four colleagues were no strangers to the abrupt reality of violent death. But this was somehow different, foreign, out of place. Bodies in a school library, blood on the books.

"It was like all of a sudden looking up and seeing the sky a different color," Battan recalls.

The bodies of 10 victims lay where they had fallen during the 71/2 minutes of madness in the library. Nearby were the bodies of Harris and Klebold, who had picked the scene of their worst carnage to end their lives.

"My God," Bodelson thought, "what happened here?"

She gazed over chairs that stood out of place and saw the scarred carpet, singed by a bomb, computer screens in pieces from shotgun blasts.

Then she looked down at the bodies on the floor. She could think of only one thing -- her own teen-age children.

"I just felt so sad," she says. "It was like I wanted to hug every one of them for their mom and dad."

This was a school, a place where kids laughed, passed notes, studied.

It was now a place where they had died.

The investigators moved through the library, not touching anything, counting the dead, snapping instant pictures of the victims, noting their clothing and physical descriptions. It was part of a process of identification. The first step.

In about an hour, Battan, West, Bodelson and Andrist finished their work and walked silently back to the main doors on the east side of the school, lost in their own thoughts.

Before they stepped out into the sunlight, Battan took a deep breath and wiped away tears from what she calls "an emotional moment."

Then she put on her game face. There was work to do.

Investigators faced a daunting task.

It was as if the toughest jigsaw puzzle they could find had been dumped on the ground, minus the box-top photograph and a handful of the most important pieces.

The amount of evidence was staggering. Any speck of blood, shard of glass or chunk of lead could prove to be crucial.

There were thousands of leads to follow and people to interview. Every kid who had been in the school could have seen something important.

Phones rang constantly at police agencies across the metro area. The tips ranged from logical to absurd. All had to be pursued.

The first challenge was to remove 15 bodies from the crime scene without disturbing vital evidence.

Directed by Andrist, 44, investigators started with Rachel Scott and Daniel Rohrbough, the two students killed outside the school.

Then they worked their way through the library, where 12 bodies lay, and afterward, the science room, where teacher Dave Sanders died.

The arduous process lasted well into Wednesday night.

Andrist divided the school into grids and organized seven evidence teams -- two for the library, one for the cafeteria, three for the rest of the building and one for the grounds outside.

He assigned experts from departments across metro Denver to the teams, making sure each had specialists in ballistics, blood evidence and other categories. Each team included a Jefferson County technician to preserve the chain of evidence.

In most criminal cases, investigators collect evidence and haul it to a vault at sheriff's headquarters. For Columbine, they brought an evidence vault to the scene -- a large trailer that sat outside the front doors for weeks.

A tent was set up outside the trailer. Each piece of evidence was brought to the tent, where it was sealed and initialed. Then it was logged and stored in the trailer.

But not everything went smoothly. Investigators swarming across southern Jefferson County were tripping over each other.

They knocked on the doors of students who'd seen shots fired, only to find another officer had just been there.

Six detectives proudly presented Battan with 1998 Columbine yearbooks.

No matter how well organized, such a huge case inevitably sparked confusion, duplication and conflict.

Even Bodelson and Thomas -- the coroner and the DA -- debated the best way to notify the families of the dead.

Thomas had the names of the 13 victims, the list assembled by comparing the forms parents had filled out the night before with the information Bodelson, Battan, West and Andrist gathered in the school early that morning.

The DA believed the list was accurate. Bodelson didn't want to take a chance.

"I have to be positive," she said.

And that meant time.

Thomas didn't think time was an option. He'd seen the shocked, confused faces of parents who hadn't found their children. And he could not keep those families waiting in fear.

So he and Bodelson agreed to disagree.

"Do what you think you have to do," she told him.

Thomas knew what to do because he'd been where these families now stood.

Three years earlier, his wife's sister had been murdered by her husband. Thomas and his wife, Shirley, brought their young niece into their home to raise as their own.

So Thomas headed to Leawood, where he found Bob Curnow, who knew all he needed from the expression on the prosecutor's face.

Later, after driving to the home of Michael and Vonda Shoels to tell them their son was dead, Thomas returned to Columbine and his moment alone with Matt Kechter.

For more than a day, ATF agent Motte, 39, waited impatiently to learn the makes, models and serial numbers of the four guns carried by Harris and Klebold.

At dusk Wednesday, as a chill wind brought sleet and then snow, an evidence technician handed him a slip of paper with the names and numbers he needed.

The killers had carried two aging shotguns, a Savage model 67H pump and a Savage model 311D double-barrel, both roughly 30 years old.

Motte knew these would be trouble -- before 1968, gun manufacturers weren't required to stamp serial numbers on weapons, making it nearly impossible to trace them. After so much time, the guns could have passed through many owners before ending up in the hands of two teen-age killers.

But Motte also caught a break. The two other weapons, a 10-shot Hi-Point model 995 carbine rifle and an Intratec TEC DC-9 semiautomatic pistol, were relatively new.

Motte called ATF headquarters and asked for an "urgent trace" on each of the four weapons.

Within an hour, the phone rang in Charlie Brown's Ohio home. Brown, vice president of a Dayton gun distributorship that sells Hi-Point weapons, was asked to look for records on the carbine.

Brown drove to his office and quickly found the paperwork. He faxed the records to the ATF agents.

Manufactured in August 1998, the carbine had gone to Brown's company, then was shipped to a dealer in Selma, Ala. It finally was sold at a Longmont gun shop.

The 1994 TEC DC-9 had gone to an Illinois sporting goods shop, then to a Colorado gun dealer. It eventually was sold at the Tanner Gun Show, held regularly at the Denver Merchandise Mart.

The shotguns proved as difficult to trace as Motte feared. The manufacturer had gone out of business, and he got no further than the original retail sale of each weapon.

It was after midnight Wednesday when Thomas walked back through his front door. In all his years as a prosecutor, in all the sad stories and ruined lives he'd encountered, he'd never completely lost control of his emotions.

Until now.

"Why did this happen?" he screamed hysterically, tears pouring down his cheeks.

His wife, a federal treasury agent, tried to comfort him.

"These children did not deserve to die," he wailed. "This is so unfair."

Amassing the Facts

Sheriff's Lt. John Kiekbusch stands in a room containing 300 binders filled with reports from Columbine investigators. Kiekbusch is directing the criminal probe of the high school tragedy, an exhaustive inquiry nearing its completion.

Two FBI evidence recovery specialists moved slowly amid a sea of backpacks on the flooded floor of Columbine High School's cafeteria.

Then they stopped.

At their feet lay two large dark gym bags, bigger than the packs terrified students had abandoned 48 hours earlier when gunshots exploded just outside the lunchroom. One bag bore scorch marks, and the ceiling tiles above it had melted.

The FBI agents delicately looked inside the bags -- and instantly understood the true intentions of Dylan Klebold and Eric Harris: death, by fire, for hundreds of their fellow students.

The gym bags each held a large bomb fashioned from a barbecue grill propane tank, a gasoline can and other fuel cylinders. Each was wired to a pipe bomb. A two-bell alarm clock served as a timing device.

Had both bombs not failed, explosives experts concluded, the 660 kids in the cafeteria at 11:20 a.m. April 20 likely would have died -- nearly four times the number killed in the Oklahoma City bombing.

A blast that size would have turned every fork, every spoon, every tray into shrapnel. A giant fireball would have roared through the cavernous room, sucking up oxygen in its wake -- making survival all but impossible.

The FBI agents' stunning discovery that morning quickly had reverberations across town.

Attorney General Janet Reno leaves a press conference at the Jefferson County Justice Center two days after the Columbine tragedy. District Attorney Dave Thomas stands at right. Reno canceled her plan to tour the school after additional bombs were discovered there.

At Jefferson County District Attorney Dave Thomas' office, newly sworn-in U.S. Attorney Tom Strickland was getting ready to bring Attorney General Janet Reno to Columbine. She wanted to walk through the crime scene.

Now, with the news that Columbine still was not secured, her visit was canceled.

Reno had come to Colorado to talk with families of the victims and the police, firefighters and paramedics who had been at Columbine.

She started with a private meeting in the small law library below Thomas' office, where sheriff's officials brought in pieces of evidence to show her.

Among them were the four guns used by Harris and Klebold, each sealed in a plastic evidence bag. She also saw photographs from the crime scene.

Someone read passages from Harris' writings.

Reno also needed a refuge, a place where she could rest. So a conference room just off Thomas' office was converted into a haven for Reno, who battles Parkinson's disease.

Juice and food were set out, along with a place where she could lie down.

But, engrossed by the day's events, she hardly used it.

A Grim Task

At five coroner's offices, pathologists began conducting autopsies.

Dr. Nancy Bodelson, Jefferson County's coroner, and her staff positively identified the victims and formally notified their families.

Then she brought in help from neighboring counties.

She wanted to finish the autopsies and release the bodies to mortuaries quickly so bereaved families could plan funerals.

By 6 p.m. Thursday, they were done.

Two days into the investigation, much of the work at Columbine remained chaotic.

But the introduction of the FBI's Rapid Start computer case-management system put the massive criminal investigation on fast forward.

The sophisticated software allowed investigators to track every lead, catalog witnesses, cross-reference evidence and put a stop to duplication.

In a hasty training session, investigators were assured the system was "Crayola simple."

A second computer system managed the blizzard of reports from investigators. Eventually, those reports would fill more than 300 heavy three-ring binders, stored neatly on wooden bookshelves in a room at sheriff's headquarters the investigators came to call "the library."

On Friday morning, the start of Day 4, John Kiekbusch, the sheriff's lieutenant directing the investigation, brought nearly 100 detectives into the Columbine band room to talk.

The room itself was a stark reminder of why they were there. A door had been blown off its hinges by a SWAT team. Instruments, backpacks and music stands lay scattered where students had dropped them.

Chris Andrist, the sheriff's crime lab supervisor, set up large easels with sheets of white paper and color-coded markers to designate different types of information.

One by one, detectives rose, introduced themselves and explained what they had done and whom they had interviewed. As their information was written down, the sheets were ripped from the easels and taped to the band-room walls.

"People were literally pulling matchbooks out of their pockets with notes they had scribbled on them," recalls FBI supervisor Dwayne Fuselier.

For investigators from every major police agency in the metro area, the mass meeting was the first opportunity to hear what everyone had learned.

It also helped Kiekbusch and his command team decide how the crime scene should be managed and how investigative teams should be formed.

The meeting went on for seven hours. Toward the end, Fuselier stood to speak.

He said he was concerned about a rumor, circulating among investigators, that the FBI was taking over the case.

"We are often seen as the 800-pound gorilla, and I wanted people to know we were not trying to take over the investigation," he recalls. "I made it clear we were there to assist in whatever way we could.

"This is Jeffco's case all the way."

A Mentor's Legacy

John Kiekbusch had come a long way to run the Columbine investigation.

He had started almost 30 years earlier, in the infancy of the Lakewood Police Department, under Pierce Brooks, a legend in national police circles.

Brooks had gained fame in Joseph Wambaugh's book The Onion Field for investigating the 1963 murder of a Los Angeles police officer by two drifters. He later helped the FBI create a serial crimes unit.

Brooks became Lakewood's second police chief in 1971, taking the job as a challenge to craft an efficient, professional police department almost from scratch.

He recruited talented officers from around the country. One of them was Kiekbusch, then a 25-year-old patrolman in Winona, Minn. He landed in Brooks' robbery-homicide squad.

Brooks, who died in 1998, believed that the answer to almost every homicide lay in the evidence at the scene.

"Murder is the greatest challenge," he once said. "You can't close your mind. You have to wonder what kind of person would act like this. You have to get inside the killer's brain."

He drilled that perspective into every cop who worked for him. Kiekbusch was no exception.

A Critical Tape

By Friday night, FBI agent Mike Barnett, Jefferson County sheriff's Sgt. Don Estep and Colorado Bureau of Investigation agent Linda Holloway were on a commercial jet to the East Coast.

Their destination: FBI headquarters in Quantico, Va. Their cargo: The videotape from a surveillance camera in the Columbine cafeteria.

FBI technicians were waiting to analyze the film frame-by-frame and enhance the images.

It was important work. The tape might show whether someone other than Harris and Klebold had carried a gun or bombs into the school that day.

The three officers met the FBI technicians early Saturday morning. Late Sunday night, they hurried back to the airport to catch a flight to Denver, the enhanced tape in hand.

They had watched every second of the black-and-white tape, over and over again. It showed students hiding beneath tables, then running to safety.

It also showed Harris, in a white T-shirt, kneeling on the landing outside the cafeteria, firing his 9 mm Hi-Point carbine at the bomb.

The images helped investigators reconcile statements from students who saw a gunman in a white T-shirt and Harris in a trench coat. Harris, it turned out, had shed his trench coat outside the school's west doors as he and Klebold walked in.

It also showed Klebold -- who'd left his trench coat behind in the library -- wearing a black shirt and tossing a pipe bomb at one of the propane-tank bombs. Klebold dove behind some tables as the pipe bomb exploded, setting off sparks, filling the deserted cafeteria with smoke and starting a fire.

What it didn't show was that by the time the killers reached the cafeteria, their detailed plan had gone awry.

Their huge bombs hadn't exploded as planned -- when the cafeteria was full of students between 11:15 and 11:20 a.m.

So Harris and Klebold had started shooting on a hill outside the back door to the library, killing two and wounding eight others. Then they'd gone in the west doors, shooting a student at the far end of a hallway and fatally wounding teacher Dave Sanders.

Next, they'd barged into the library, where they killed 10 students and wounded a dozen more.

Then, the cafeteria tape showed, they went downstairs to try to detonate their balky bombs.

One question couldn't be answered: Did they intend to die in the fireball certain to result from the detonation of the bombs?

Investigators found booby traps in Dylan Klebold's BMW, above, parked in the high school parking lot. Similar explosive devices also were found in Eric Harris' car nearby.

But the discovery of the cafeteria bombs, along with explosives found in the cars Harris and Klebold drove to Columbine, gave investigators fresh insight into the havoc the two teen-agers hoped to rain on their school.

Each of their cars, investigators found, was rigged with explosives timed to blow as police officers, firefighters and paramedics arrived on the scene.

Harris left his car in a space along the access driveway into the school from Pierce Street. Klebold's vintage BMW was parked not far from the cafeteria, seven spaces from the end of a row of cars teeming with officers after the first call for help went out.

The "War Room"

Monday morning, six days after the tragedy, the task force moved from Columbine to its new home at the Taj Mahal, the nickname for the Jefferson County government building in Golden. County commissioners cleared out west-wing offices to make room.

The area would be collectively known as the "war room," but it was actually several rooms. One, about 20 feet by 20 feet, held only computers -- Rapid Start, word processors and machines that let investigators access the Internet and the Colorado and national crime databases. Another was divided -- part work space, part telephones. Three other rooms housed investigators.

The CBI, which handles most lab work for police and sheriff's departments across the state, took on the ballistics testing. It was a big job -- evidence recovered at the school showed that Harris and Klebold fired nearly 200 rounds.

More than 100 rounds had been fired by law officers -- both those who briefly engaged in gunfire with the killers and the SWAT teams that laid down cover fire and, in some cases, blew open doors as they searched the school.

Technicians test-fired every weapon used at Columbine, then compared every bullet, fragment and shell casing. The work tied each round to the weapon that fired it.

The federal Bureau of Alcohol, Tobacco and Firearms, which traces 200,000 guns a year, tracked the histories of the four weapons Harris and Klebold had used. In addition, the ATF tackled lab work on all explosives recovered from the school and the cars and homes of Harris and Klebold.

Investigators found more than 80 bombs.

Some were pipe bombs. Others were fashioned out of propane canisters and CO2 (carbon dioxide) cartridges. Investigators even found some explosives containing homemade napalm, a jellied form of gasoline.

The huge number of bombs led some -- including Sheriff John Stone -- to believe that Harris and Klebold must have had help.

But because many of the devices were so small, investigators eventually concluded that they could have easily been carried into the school in duffel bags.

Team by Team

A vital step for task force leaders was to assign investigators from 12 local and federal agencies to six teams examining specific aspects of the crime.

Arvada police detective Russ Boatright was picked to lead the Library Team, responsible for unraveling the mysteries in the room where Harris and Klebold did most of their killing.

Boatright, 40, was no stranger to kids and guns. In 1991, a 14-year-old pulled a pistol on him in a junior high school in Arvada. Boatright subdued him and took the weapon away.

FBI Agent Rich Price, 38, would run the Cafeteria Team. It would interview nearly 700 kids who had been in the lunchroom that morning.

Price, an ex-Marine, helped investigate the Oklahoma City bombing in 1995.

Estep, 49, would lead the Friends and Associates Team.

An undercover cop who specialized in examining radical organizations, Estep favored jeans and work shirts over the suits and ties of his FBI colleagues. With a full beard and shock of dark unkempt hair, Estep looked as if he could walk into any biker bar and never draw a suspicious glance.

But his appearance belied a hard-headed attitude toward crime that had earned the respect of officers across the metro area during his 27-year career.

Estep's team would look at every friendship of Harris and Klebold, every co-worker, anyone who had regular contact with them or knowledge of their activities.

FBI agent Mike Barnett was handed the Outside Team.

The 30-something Barnett was the youngest team leader. But he already was a veteran of Fuselier's domestic terrorism squad and known for thoroughness.

His team would retrace the movements of Harris and Klebold the day of the shootings, from the time they got up to their arrival at the school and their first bursts of gunfire on the hill outside the cafeteria, where they shot 10 victims. The team's work would stop at the point the killers entered the school behind a hail of bullets.

CBI agent Chuck Davis, 35, would lead the Computer Team. He had joined CBI in February 1995 after three years with the Air Force Office of Special Investigations, where he handled counter-espionage and child-pornography investigations.

From the time he built a computer from a kit in high school, Davis had had a passion for these magical machines. But he also carried a gun, served search warrants, kicked in doors and made arrests.

After a personnel shuffle, leadership of the Threats Team would fall to sheriff's Sgt. Rich Webb, 49. His job was to assess threats of school violence made after the Columbine tragedy, a task that eventually involved FBI agents across the country.

With teams in place, computer programs organizing vast amounts of data and evidence collection well under way, the investigation leaped forward.

Three days after the tragedy, sherriff's spokesman Steve Davis plays a tape of a 911 call made during the shootings. Saturation media coverage made Davis a worldwide symbol of the law enforcement response to Columbine.

A Media Horde

As investigators moved through southern Jefferson County to interview witnesses and victims, they had company.

A crush of local, national and international media -- television, radio, newspaper, magazine and free-lance reporters, producers and camera crews -- dogged their tracks.

Investigators often saw reporters leaving the homes of witnesses as they arrived or arriving as they left.

Steve Davis, the sheriff's spokesman who became the official face of the investigation around the world, couldn't keep up with the demand for interviews.

In the first 30 days, his pager beeped 1,300 times.

Dozens of times, detectives had to conduct follow-up interviews with students after the kids told reporters something different than they'd told investigators.

Controversy even erupted inside the investigation.

Less than three weeks after the shootings, as the media jockeyed for new leads, Inside Edition, a national TV news entertainment show, aired a two-year-old videotape made for a class by four Columbine students.

It was a spoof, depicting a secret agent battling a mad scientist trying to blow up the school. But scenes of explosions at Columbine and a gun-toting student in a raincoat took on a sinister, almost prescient, tone in the wake of the killings.

Reporters then discovered that FBI agent Dwayne Fuselier's oldest son, Scott, by then a university student studying filmmaking in California, had created the video in a class editing project.

Fuselier told Kiekbusch and Sheriff's Capt. Dan Harris, another investigation leader, about the origins of his son's tape.

Don't worry about it, they told him.

But days later, the Denver Rocky Mountain News interviewed Brooks Brown, a longtime friend of Harris and Klebold who was identified shortly before by Sheriff Stone as a potential suspect. Brown said he had helped edit the videotape.

ANews editorial, noting the link to Brown, criticized the FBI and Fuselier for refusing to talk about the issue and for downplaying a potential conflict of interest. Though they didn't say it publicly at the time, Fuselier and other officials now acknowledge they discussed it.

Fuselier offered to quit the case if the tape compromised his role.

Forget it, Kiekbusch said. If everyone with a link to Columbine quit the task force, there'd be no one left.

Later, the teen-ager admitted that he'd lied about having been involved with the tape, Fuselier says -- and Brown's family acknowledges. The tenuous link that tied Fuselier's son to the killers never existed.

"There was absolutely nothing whatsoever to connect Dwayne's son to Harris and Klebold or to the event itself," Kiekbusch says.

Nevertheless, the saturation coverage of Columbine continued.

Weeks into the investigation, when Kiekbusch was finally getting five hours of sleep a night, he left his house early one morning. A man rushed up to him in his driveway.

"He introduced himself as Mr. Ono," Kiekbusch recalls, "a reporter for Japanese television. He insisted I tell him ... (about) the case."

Kiekbusch was already weary of daily calls from reporters, answering the same questions, over and over.

"Oh, no," he thought. "Now they're going to be waiting outside my house."

Kiekbusch's boss, Sheriff Stone, was having his own problems with the press.

In the first weeks, he was accessible, sometimes even eager to speak with reporters. He was usually frank, laying out his belief that investigators would find that Harris and Klebold had accomplices. It led to an uncomfortable scene one night after Stone granted an interview to a wire service reporter.

The story left the impression that arrests were imminent. Faced with questions from scores of other reporters, a sheriff's spokesman drove to Stone's house, got him out of bed and drove him back to Columbine to backpedal for the press.

Stone, 50, is an unusual breed -- part cop, part politician.

A former Lakewood police officer, Stone won a seat in 1986 on the Jefferson County Commission. He won two more four-year terms.

Then, in 1998, he ran for sheriff -- without the endorsement of the Fraternal Order of Police -- and won. He took office in January.

As a county commissioner, he'd grown comfortable speaking in public and granting interviews. But after his officers were asked, more than once, to respond to statements he'd made early in the Columbine investigation, his top aides privately urged him to say less.

Cops, by nature, are secretive. In the biggest criminal case in state history, some didn't want to divulge anything publicly. Others felt compelled to offer details to a stunned nation.

Stone also faced public criticism for some of his statements, including his speculation the first afternoon that the death toll could reach 25 and that Harris and Klebold probably had accomplices.

Today, Stone defends himself, saying he was merely giving out the best information available at the time.

That first afternoon, he notes, a teacher told investigators there was a "whole bunch" of kids shooting up the school.

It angers him that he was criticized by the same people who clamored for information -- reporters.

Months later, after assuming a lower profile, Stone said he didn't regret his blunt comments early on.

"I think the public's got a right to know," he says.

Biggest Question of All

Detective Kate Battan walked into a small office, carrying three videotapes.

The tapes, with perhaps three hours of footage, had been confiscated from the home of Eric Harris.

Battan, lead investigator in the Columbine High School shootings about 10 days earlier, dimmed the lights.

Up popped the young killers on the television screen, cocky and confident.

The teen-agers sat on a couch speaking into the camera, weeks before their murderous assault.

There was no doubt whom the boys were addressing. They kept referring to "you detectives."

We're doing this alone, they said, again and again.

And they made another point: They had begun planning their rampage long before the spate of school shootings across the country.

We're no copycats, they said. Those other kids? They're copying us.

If their boasts were true, their plan to assault Columbine had started more than two years earlier -- before the shootings in Springfield, Ore.; Jonesboro, Ark.; West Paducah, Ky.; and Pearl, Miss.

The Series

Sunday: The first fragmentary reports of shooting at Columbine bring more than 600 police officers face to face with the unthinkable.

Monday: After 48 chaotic hours, specialists from a dozen agencies are organized into teams to launch a methodical examination of the crime.

Today: As they near the end of eight months of intensive work, investigators still grope for an answer to the biggest question of all.

The images and voices of the boys stunned Battan, an investigator who had moved in recent years from complex, white-collar and financial crimes to high-profile homicides.

In 1998 alone, the sheriff's detective had been involved in two of the most sensational cases in Jefferson County history -- the murder of two children by their mentally ill mother and a triple ax-slaying at a townhome over Fourth of July weekend.

But now, months later, even that experience couldn't ease the horror that eneveloped her in the darkened room as she watched Harris and Dylan Klebold speaking, it seemed, directly to her from the grave.

The images spooked Battan so much she turned the lights back up before the tapes finished.

"It just flabbergasted me," she says, "that so much evil came out of these two teen-age boys."

The release this week by Time and the Denver Rocky Mountain News of printed excerpts of the videotapes gave the public a detailed glimpse at the criminal minds of the two killers. But the printed words don't convey the cold, calculating tone of the boys' voices.

In their soliloquies, Harris and Klebold thanked two friends who had helped them get the semiautomatic pistol they'd used at Columbine. The boys urged investigators not to press charges against the two.

"If they wouldn't have f------ helped us out, then we would have found someone else," Harris bragged. "We would have gone on and on. We would have found some way around it, 'cause that's what we do."

In the months ahead, Battan would come to see this as the quintessential philosophy of the two boys: "That's what we do."

"That," Battan says, "is Eric Harris and Dylan Klebold."

Guns and Bombs

For explosives specialist Doug Lambert of the federal Bureau of Alcohol, Tobacco and Firearms, Columbine was everything he'd ever trained for. His job was simple: make sure more bombs weren't planted in the school.

Two of Lambert's colleagues were unlike any others.

Jenny and Cascade, Labrador retrievers from Virginia, were specially trained to sniff out chemicals found in bombs and bullets. ATF agents used them to check each locker, air duct, ceiling and backpack.

The agents examined the scores of bombs -- exploded and undetonated -- found inside the school. They used a computer program to map where fragments were recovered.

"We basically put all the pieces back together again," says Jerry Petrilli, head of the ATF's firearms group in Denver.

Local bomb experts defused those that didn't explode.

As they went, ATF agents cautiously packaged each device -- or what was left of it.

But flying the mass of material to the ATF's national bomb laboratory in Walnut Creek, Calif., was too dangerous. Instead, agents loaded the bombs into a light brown Ford Explorer and drove them to California.

On the scene for more than a week, Lambert came away thankful that Harris and Klebold knew little about building bombs.

They didn't understand explosive reactions. They didn't understand electrical circuitry.

None of the four bombs wired with timing devices -- two in the cafeteria and devices in the killers' cars -- exploded as planned.

The Killers' Suppliers

While bomb experts unraveled explosives evidence, ATF agent Marcus Motte and other investigators tracked the guns.

Investigators, talking to everyone who knew Harris and Klebold, quickly determined how the guns got into the killers' hands.

Three days after the killings, two ATF agents met with Nate Dykeman, an 18-year-old friend of Harris and Klebold.

Dykeman provided some of the first clues to the path of the guns, telling investigators that two weeks before the shootings, he'd seen Harris with a videotape in one of their classes at Columbine. The tape showed Harris and Klebold firing guns at a shooting range in the mountains.

Also on the tape, Dykeman related, were scenes showing Philip Duran, 22, and a friend of his named "Mark" firing two shotguns. Duran worked with Harris and Klebold at a Blackjack Pizza parlor about a mile from the high school.

Two days later, Motte interviewed Duran.

Duran told the ATF agent that Harris and Klebold had approached him in January, eager to buy a gun. Duran gave them the phone number of a guy he knew named Mark Manes.

Duran said he collected money from Harris and Klebold and gave it to Manes as part of the sale of a TEC DC-9 9 mm semiautomatic pistol, a gun Klebold fired 55 times at Columbine, killing four and wounding two. It was also the gun that ended his life.

After the shootings, realizing Harris and Klebold had used the gun he'd sold at Columbine, Manes hired an attorney and decided to cooperate with investigators.

On April 30, on the sixth floor of the Federal Building in downtown Denver, Manes and his attorney met with Motte and other investigators.

Manes told them he had purchased the weapon at a 1998 gun show and acknowledged that he'd been introduced to Harris and Klebold by Duran.

Manes said he sold the gun to the killers on Jan. 23 for $500.

Manes was sentenced Nov. 12 to six years in prison for selling the gun to Klebold and Harris and for firing a sawed-off shotgun with them weeks before the massacre. Duran faces similar charges.

Investigators also tracked two shotguns and a carbine from Harris and Klebold to Robyn Anderson, 19. She'd been Klebold's prom date three days before the attack.

But Anderson, who admitted buying the three guns for Harris and Klebold at the Tanner Gun Show in Denver, has not been charged.

Federal law prohibits the "straw purchase" of a firearm on behalf of someone who is ineligible to buy it. The two killers were underage.

But the law applies only to guns sold by a licensed federal firearms dealer. ATF agents have determined that Anderson bought two of the three guns from a private person -- not a dealer. But they have not found who sold Anderson the third gun.

If that person turns out to be a licensed dealer and Anderson falsified documents to disguise the purchase, she still could face charges.

The Library Team

As Arvada police detective Russ Boatright took his team into the school library for the first time, technicians were still photographing, cataloging and collecting debris.

"We actually had an idea of what happened before we went in there," he says. "But it doesn't actually hit you until you see it."

At 40, Boatright had been a cop for more than 17 years. He'd seen plenty of misery, including crimes against children.

But the blood-spattered room stunned even him.

At first, he could not imagine the terrifying minutes in the library on April 20 -- smoke choking the air, a fire alarm blaring, strobe lights flashing, gunshots ringing out, one after another.

But soon it would become painfully real to him.

Boatright's team had the benefit of one incredible piece of evidence -- the tape of a 911 call made by Patricia Nielson, a teacher Harris wounded. She'd been shot near the school's west doors, where the gunmen entered, then had crawled to the library and grabbed a phone.

Despite the wail of the fire alarm, investigators were able to enhance the tape.

What they retrieved was an audible record of terror, one gunshot at a time. The tape showed that the shooting in the library was over in 71/2 minutes.

Starting with a rough sketch, investigators asked the 40 kids and four teachers who had survived the library massacre to draw in their recollections.

Boatright kept track of the developing story with color-coded markers -- red for the dead, blue for the wounded, green for the survivors who escaped physically unharmed.

The FBI sent experts to Columbine from Virginia to construct an elaborate model of the school. They took back rough drawings and detailed measurements.

They returned in midsummer with a diorama of the cafeteria and the library above it. It was exact -- down to the bookshelves that divided the library into three sections and the trees standing outside.

Boatright's team started interviewing everyone.

"Nobody saw everything from A to Z," he says.

The physical barriers in the room -- bookshelves and desks -- and the terror accentuated the reality that no two people ever see an event exactly the same way.

It reminded Boatright of a collage that hangs in a hall at Columbine.

A teacher assigned students to photograph a tree. Each kid snapped pictures from various angles. When they put all the pictures together, the composite image depicted the entire tree, each slice a different size, from a different perspective.

To clear up the inconsistent library accounts, the team launched an excruciating process -- taking the survivors back inside.

For the traumatized kids and their parents, it was an appalling scene: dried blood on the floor and walls, name tags marking the spots where students fell.

The investigators asked the survivors to crawl back under the tables where they had ducked for cover. Then they joined them, on hands and knees, to see it how the survivors had seen it.

One of the most noted episodes in the library had been a reported exchange between student Cassie Bernall and one gunman.

"Do you believe in God?" the gunman asked.

"Yes, I believe in God," Cassie replied.

"Why?" the gunman said, then pulled the trigger.

But student Emily Wyant, who had crouched under a table beside Bernall, told investigators the conversation never happened.

Later, with student Craig Scott, who'd escaped from underneath a table where two classmates died, investigators' doubts grew.

Scott is the brother of Rachel Scott, who had been killed outside the school. He had been a few feet from Cassie and thought it was her voice he heard.

But when he revisited the library, he realized the voice had come from another direction -- from the table where student Valeen Schnurr had been shot.

Investigators came to believe it was probably Valeen, who survived, who told the gunman of her faith in God.

Reconstructing events in the library drained Boatright and his team. They gradually realized how vulnerable everyone had been that day.

"When you see the room, you see that no one was really hiding," Boatright says.

One question could not be answered: How did Harris and Klebold pick their victims?

Under one table, they'd gun down two kids, only to leave a third physically unscathed.

"None of it makes sense," Boatright says. "Realistically, they could have gone through that library and shot every single person."

The Cafeteria Team

When investigators filed into the cafeteria Harris and Klebold had planned to incinerate, its floor was still soggy from sprinklers that sprayed for hours after the fire alarms sounded six days earlier.

A musty stench hung in the air. Food cluttered the tables; 450 backpacks littered the room.

Nine-year FBI veteran Rich Price and his 25-member crew started to identify every student who had been in the cafeteria. A list provided by the school district indicated each student who had an A-period lunch hour. But many of them had gone home or to restaurants to eat.

Investigators went from one student to another. Each would give them a new handful of names to track down.

Some visits would last 15 or 20 minutes, others hours.

Just as it had in the library, technology gave a helping hand.

The surveillance camera in the lunchroom captured the arrival of Dave Sanders, the teacher who was fatally wounded minutes later. It also recorded the exodus of the students, and -- finally -- the arrival of Harris and Klebold.

By the time they were finished, investigators had developed a seating chart that placed everyone in the cafeteria, exactly where they were when shots rang out.

"It was like dropping 700 toothpicks -- give or take -- and putting them back in the box, exactly the way they were," Price says.

The Computer Team

In a laboratory off Kipling Parkway in Lakewood, in what looks like the back room of a computer repair shop, Colorado Bureau of Investigation computer expert Chuck Davis went to work.

Behind a locked door, shaded by drawn blinds, Davis and his investigators analyzed the computers seized from the Harris and Klebold homes and elsewhere, tracing their data, uncovering their digital secrets.

Davis was well-suited to the job. When he joined the CBI four years earlier, he became the first investigator outside the Internal Revenue Service and the military to look at computer crime in Colorado.

Just hours after the Columbine killings, Davis went to Harris' home, where detectives seized the killer's computer. It became evidence item No. 001.

In the next few weeks, the team confiscated 18 other computers and 5,000 disks, most from friends of the killers. Three of the computers were taken from Columbine High: the school's main server and two machines in the media laboratory where Harris and Klebold often worked.

They pored over e-mail among Harris and Klebold and friends. Most of the writings spoke only of teen-age concerns. Girls. Games. Television shows.

The investigators scrutinized Web postings and other writings -- some from Harris' computer -- promising more death on April 26, a threat that never materialized.

Unlike Harris' computer, Klebold's offered no help.

Investigators concluded that Klebold had gutted the machine, erasing one of the two hard drives, leaving it blank.

"I can't prove it," Davis says. "But deep down in my heart, I think it was probably nuked either the day before, or that morning."

What did Klebold have to hide?

"We'll just never know," Davis says.

Investigators concluded that other computers probably were tampered with after April 20 and before they were seized.

They found scores of Internet and e-mail threats related to Columbine -- everything from "I was there and helped shoot the kids" to "There are pipe bomb instructions at this Web site."

They tried to track down what they dubbed a "master school bombing list" only to discover it didn't exist.

When a kid in New York posted an Internet message claiming that he'd been at Columbine, cops kicked in his door and took his computer.

"We took it seriously," Davis says. "I like to think cops have a sense of humor, but when you're dealing with a bunch of dead kids, our humor factor was zero."

The computer team found no evidence to suggest that anyone knew about the macabre plans of Harris and Klebold -- or helped carry them out.

But the investigators destroyed a myth:

Harris and Klebold weren't the computer experts they had been made out to be. They were good, Davis says, but other kids could do much more.

The Outside Team

In the moments before Harris and Klebold began their assault, some students had dropped their backpacks and gone outside to play on the soccer field. Some had left campus. Others took advantage of the sunshine to have lunch on the grass.

Mike Barnett's team eventually identified 100 witnesses outside the school, not including law enforcement officers.

"The main thrust was to interview witnesses to determine the sequence of events," the FBI agent says. "Who was where, who shot whom, who did what."

To do that, the team turned to the FBI's special projects unit on the East Coast. They developed a four-foot-by-five-foot, computer-generated schematic with plastic overlays locating all the outside witnesses, victims and police, and what they had seen.

They tracked down school janitors and maintenance workers from Clement Park next to the school. They found people who had walked past the school or through the parking lots that morning.

And they waited patiently for the chance to interview those who were seriously wounded.

Some witnesses had seen Harris and Klebold arrive in the parking lot. But no one had seen them carry two large duffel bags inside minutes later and set them down in the cafeteria.

Barnett and his team discovered, through sales receipts, that Harris and Klebold had filled the two large propane tanks for their cafeteria bombs the morning of the attack.

The Outside Team also interviewed every police officer outside the school that day, including sheriff's deputies Paul Smoker and Neal Gardner, who briefly traded shots with Harris and Klebold. Team members also interviewed nine other officers who fired their weapons at Columbine on April 20.

The investigators dispelled several claims by witnesses, including one about a rooftop sniper.

The man on the roof, it turned out, was an air conditioning repairman who quickly hid when the shooting started. He saw virtually nothing.

The Friends and Associates Team

The day of the shootings, television crews captured video of three young men in a field near the school. They were wearing military fatigues and walking toward the scene. Police with bulletproof vests and shotguns handcuffed them and led them away.

"Let the media chase those guys," said sheriff's Sgt. Don Estep, who soon took charge of the Friends and Associates Team.

After 27 years as a Jeffco sheriff's deputy, much of it in the shadowy world of undercover intelligence, Estep knew almost by instinct that the young men probably weren't involved. He was right. Investigators quickly eliminated the three as potential suspects.

But ruling out other suspects, those who were friends or associates of Harris and Klebold, would be far more difficult.

The team was confronted by reports that as many as eight gunmen had been in the school. Some witnesses reported seeing someone besides Harris and Klebold firing a weapon inside.

There also were dozens of tips that Harris and Klebold had help carrying pipe bombs into the school and possibly planning the attack.

Investigators visited the homes of witnesses and potential suspects.

They kept hearing the same things about Harris and Klebold: They were smart, they were partners and they kept most of their business -- especially their plot -- to themselves.

To verify alibis, investigators asked several friends of Harris and Klebold to take polygraph tests.

"We certainly used the lie detector as a tool to clear individuals of involvement in this," says Mark Holstlaw, an FBI agent who worked closely with Estep on the team. "Some agreed, some declined, some had their own done. For those who declined, we used other investigative methods to clear them."

Speculation about additional suspects continued for weeks.

One Denver television station repeatedly showed videotape of a friend of the gunmen being put into the back of a squad car by police on April 20. The reports implied that arrests of co-conspirators were imminent.

But except for Manes and Duran, no other arrests came.

The Threats Team

Sgt. Rich Webb, a 24-year law enforcement veteran, missed the first hours of Columbine. April 20 was his day off, and he was in his back yard, landscaping. When sketchy reports of a shooting at Columbine interrupted music he was listening to, he called the office.

"This is bad," he was told. But a supervisor told him to stay home and rest. We'll need fresh people tomorrow.

Webb, a former SWAT team leader, grumbled and threw rocks around his yard the rest of the afternoon. The biggest case of his career and he was out of the loop.

But not for long.

He spent the next two days working with the coroner to identify the dead and assist with autopsies.

By the time he moved onto the Threats Team six days after the shootings, menacing messages were pouring in. From the Internet. From the phone. From other schools in the area.

At a middle school in Arvada, a student trying to be funny left what looked like a bomb in a bathroom. He had wrapped a plastic box in aluminum foil and taped nails to it.

At an Arvada high school, a woman angry about her son's treatment by athletes phoned in a threat.

In Broomfield, a boy sent a threatening e-mail to the Columbine memorial organization.

Webb's team tracked them all down.

Some threats actually were innocent statements that eventually took on a sinister tone.

One happened at Chatfield High, where many of the emotionally fragile Columbine students were finishing the school year.

"You could bring something into this school," one kid told another, emphasizing what he saw as a lack of security.

Someone overheard the remark. Then it was repeated, again and again.

By the time Webb's team heard it, two kids were plotting to bring in weapons and bombs.

The investigators sped to Chatfield. As they rushed in, they found hallways packed with frightened students.

"The panic was ready to go," Webb says. "These kids were on edge ... ready to go out that door. Somebody could have snapped their fingers loudly and those kids would have bolted."

Much of the Threats Team's work was tracking information to its original source.

"We would run from rumor to rumor to rumor," Webb says.

After two weeks of chaos, leads began to taper off. By the time the team finished, it had investigated 202 threats.

The threats led to six arrests in the United States and Canada. Eleven students were suspended from school -- nine in the Denver area, including six from Columbine.

Along the way, investigators encountered scores of kids who bragged that they were in the Trench Coat Mafia. They found other kids who sympathized with Harris and Klebold and admired their anti-social lifestyle.

"It was just absolutely bizarre," Webb says. "You had to stop and ask, 'What in the world is he talking about?"'

Investigators' aggressive response to the loose talk sometimes crashed head-on into concerns over the right of free speech. Some cops found it disturbing that people could write anything in support of two teen-agers so full of hate that they planned -- as U.S. Attorney Tom Strickland put it -- "to become the biggest mass murderers in United States history."

On Their Own

As months wore on, detectives focused not only on what happened at Columbine, but on what didn't happen.

After analyzing more than 3,500 pieces of evidence, from bullets and spent shell casings to blood and fingerprints, Colorado Bureau of Investigation technicians ruled out one fear -- that some victims might have been hit by "friendly fire" from police guns.

They also ruled out the existence of a third gunman.

Many detectives had believed from the start that Harris and Klebold had acted alone.

Confirmation came in late July with the CBI's final ballistics reports.

Every bullet or fragment matched one of the four guns used by Harris and Klebold or weapons fired by police.

Only one conclusion could be drawn: There was no third gunman.

But ballistics evidence could not answer other key questions.

Had anyone known that Harris and Klebold planned to attack the school on April 20. Had anyone helped?

No evidence supported either possibility.

"Are you ever completely sure?" asks FBI agent Dwayne Fuselier, an anti-terrorism specialist who helped run the investigation. "Maybe not. Could something surface in the future? I suppose. But I think I would say this, we're about 99.9 percent sure."

Drawing conclusions

Police finally got their long-awaited interview with the parents of Eric Harris in October. It came after months of quiet negotiations between the family's attorneys and District Attorney Dave Thomas.

Beforehand, investigators agreed with the Harris family and their attorneys not to say anything publicly about the discussion. They were similarly silent about their interview, 10 days after the killings, with Dylan Klebold's parents.

Now, almost eight months after their work began, here's what Columbine investigators have concluded:

Only Harris, Klebold and police fired weapons inside the school.

No one helped the killers carry bombs into the school.

The terror was relatively short-lived -- roughly 16 minutes from the first gunshot outside the school about 11:20 a.m. to the last one in the library.

Harris and Klebold probably were dead shortly after noon -- though that point is still open among investigators. What is known is that between the time they left the library around 11:36 a.m. and returned there to commit suicide, they didn't shoot anyone else.

There is no evidence of a wider Columbine conspiracy.

In fact, evidence pointed the other way. The massacre was carried out by two intelligent, secretive, cunning teen-agers who managed to keep their terrible plot to themselves.

Not everyone was convinced. Sheriff John Stone still harbors doubts.

"You'll always wonder if somebody else was involved," he says.

Despite the questions that remain, the Columbine investigation succeeded in one way no one really had foreseen: The multiagency task force became a model for other communities across the country.

"Basically, they (officers) left their badges and their egos at the curb," CBI Inspector Pete Mang says. "I've never seen that in law enforcement before."

Investigators still wonder why.

"It may have been because this thing was so big that everyone had their own piece of it," Estep says. "There was plenty of work to go around."

The nature of the event and the age of the victims also may have convinced investigators that turf battles would be pointless, unprofessional and insensitive.


In a tiny, stifling interrogation room, sheriff's Sgt. Randy West shifts uncomfortably in a gray plastic chair.

He clears his throat, crosses his legs, takes a deep breath. Now and then, tears well in the corners of his eyes, evidence of the stress of months of investigating the inexplicable tragedy at Columbine.

West, 41, is accustomed to asking questions in this room. But now, he is answering them.

This is how it was, he says, behind the closed doors of the most complex criminal investigation in Colorado history.

And this is the toll it took.

He recalls the day he realized how close two teen-agers came to accomplishing even more heinous devastation -- killing hundreds of students in the school cafeteria with two large bombs that, for some reason, failed to explode.

"I don't know why they didn't go off, and I don't care to know," West says.

A stricken look freezes on his face.

"It would have been worse than Oklahoma City. Much worse. I don't even want to think about that."

But day after day, for months, West and his fellow investigators have thought of little else.

The devastation of families, caused by two teen-age boys, the grief, the horror, the impact on investigators themselves, have all come to rest like an unrelenting weight upon their shoulders.

"We're all tough and mean," he says. "But if you don't learn how to deal with the things you saw in the library, it will eat you up.

"Right now, I just want it to be finished. Then I'll think about the impact on me."

The final report of the investigation task force will be made public in the next few weeks and forwarded to Gov. Bill Owens' Columbine Commission. That panel will review the investigation and the response to the disaster at Columbine.

But the criminal case will be left open indefinitely. There is no statute of limitations on murder.

Investigators had hoped to keep sealed some of the most gruesome and shocking evidence, including crime scene photographs and the Harris-Klebold videotapes.

Leaving the case open, investigators had hoped, also would allow investigators to keep sealed some of the most gruesome and shocking evidence, including crime scene photographs and the Harris-Klebold videotapes.

Their reasoning was simple.

First, they wanted to protect the integrity of the evidence in the event anyone comes forward with new information.

Second, they didn't want to do anything to hurt the families of those injured and killed at Columbine -- families the investigators had come to know well and care about.

But now the Sheriff's Department has made the videotapes public, and it's unclear what impact that will have on the disclosure of remaining evidence.

No matter how exhaustive, the official report will never tell the entire story or measure the deep scars this tragedy left on the victims and the community.

It won't say that Coroner Nancy Bodelson still struggles to retain her composure when she thinks about the kids on the floor of the Columbine library.

Or that John Kiekbusch, commander of the investigation, worries that the community may yet face the same phenomenon that played out after the Oklahoma City bombing: suicides among police officers, paramedics and firefighters who rushed to the scene.

Or record the chill investigators still feel when they consider that the cafeteria bombs could have killed hundreds of children.

Or show the look on District Attorney Dave Thomas' face when he recalls the eyes of a broken-hearted father, just informed his son was dead.

Or explain why Sgt. Rich Webb and others wonder when -- not if -- someone will try to outdo Harris and Klebold.

Or finally answer the one question that remains on everyone's lips:


"I think I know why they did it," the FBI's Fuselier says. "It was because they were so filled with hate.

"But the real question is why they had so much hate inside them."