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.