Dave Cullen - Columbine

The interrogation went on for four hours. Robyn held her ground.

Bomb squads had been through the school several times and found nearly a hundred bombs of varying sizes and composition—most exploded, some not. Most were pipe bombs or crickets, but one in the cafeteria stood out: a big white propane tank, standing upright, nearly two feet tall. It was wedged against a one-gallon gasoline can. The most ominous part was the alarm clock. There were remnants of an orange duffel bag, too, mostly burned away. The car bombs were also discovered, with more faulty wiring. The diversionary bomb in the field was disturbing for another reason. It had blown shortly after being moved, suggesting booby traps. Trip wires could be anywhere.

The FBI provided a group of crime scene specialists to assist in the massive effort of documenting the evidence. At 8:15 on Thursday morning, the team slogged through the cafeteria debris. Hundreds of backpacks, lunch trays, and half-eaten meals had been abandoned, many of them knocked over, singed by fire, or scattered by explosions, and everything had been soaked by the sprinkler system, which had run for hours. Muted pagers buried inside the backpacks beeped methodically, alerting the kids to phone home.

As they walked, an agent spotted a blue duffel bag ten feet from the burned-out orange bag with the big bomb. It was bulging and sized to fit the same contraption. They walked over. One of the agents pressed down slowly on the top. Hard. Probably another tank. They called help over: a couple of deputies and an FBI bomb technician. One of the officers was Mike Guerra, the same man who had investigated Eric Harris a year earlier. He sliced open the bag. They could see the end of a propane tank and an alarm clock that matched the other. There were still active bombs in here. How many more? They closed off the area immediately.

Had the propane bombs detonated, they would have incinerated most or all of the inhabitants of the commons. They would have killed five hundred people in the first few seconds. Four times the toll in Oklahoma City. More than the ten worst domestic terrorist attacks in U.S. history combined.

For investigators, the big bombs changed everything: the scale, the method, and the motive of the attack. Above all, it had been indiscriminate. Everyone was supposed to die. Columbine was fundamentally different from the other school shootings. It had not really been intended as a shooting at all. Primarily, it had been a bombing that failed.

That same day, officials announced the discovery of the big bombs, and their destructive power. It instigated a new media shock wave. But, curiously, journalists failed to grasp the implications. Detectives let go of the targeting theory immediately. It had been sketchy to begin with, and now it was completely disproved. The media never shook it off. They saw what happened at Columbine as a shooting and the killers as outcasts targeting jocks. They filtered every new development through that lens.

Dylan Bennet Klebold was born brilliant. He started school a year early, and by third grade was enrolled in the CHIPS program: Challenging High Intellectual Potential Students. Even among the brains, Dylan stood out as a math prodigy. The early start didn’t impede him intellectually, but strained his shyness further.

The idealistic Klebolds named their two boys after Dylan Thomas and Lord Byron. Tom and Sue met at Ohio State University, studying art, Tom in sculpture. They moved to Wisconsin and earned more practical master’s: Tom in geophysics, Sue in education, as a reading specialist. Tom took an oil job and moved the family to Jeffco, before the Denver metroplex stretched out to reach them.

Dylan was born there, five months after Eric, September 11, 1981. Both grew up as small-town boys. Dylan earned merit badges in the Cub Scouts and won a Pinewood Derby contest. Sports were always big. He was a driven competitor, hated to lose. When he pitched in Little League he liked to whiff hitters so badly they tossed their bats. He would idolize major leaguers until the day he died.

The Klebold house was orderly and intellectual. Sue Klebold was a stickler for cleanliness, but Dylan enjoyed getting dirty. A neighbor—the woman who would struggle so hard to stop Eric before the massacre—fed Dylan’s early Huck Finn appetite. Judy Brown was the neighborhood mom, serving up treats, hosting sleepovers, and rounding up the boys for little adventures. Dylan met her son Brooks in the gifted program. Brooks had a long, egg-shaped face, like Dylan’s, narrowing at the jaw. But where Dylan’s eyes were animated, Brooks’s drooped, leaving a perpetual weary, worried expression. Both boys grew faster than their classmates—Brooks would eventually reach six-five. They would hang out all afternoon at the Browns’ house, munching Oreos on the sofa, asking Judy politely for another. Dylan was painfully shy with strangers, but he would run right up, plop down in her lap, and snuggle in there. He couldn’t be more adorable, until you tripped his fragile ego. It didn’t take much.

Judy first saw him blow when he was eight or nine. They had driven down to a creek bed for a typical adventure. Sue Klebold had come along—horrified by all the mud, but bearing it to bond with her boy. Officially, it was a crawdad hunt, but they were always on the lookout for frogs or tadpoles or anything that might slither by. Sue fretted about bacteria, hectoring the boys to behave and keep clean.

They’d brought a big bucket to haul the crawdads home, but came back up the hillside with nothing to show. Then one of the boys slogged out of the creek with a leech attached to his leg. The kids all went delirious. They plopped the leech into the frog jar—a mayonnaise bottle with holes punched in the lid—and watched it incessantly. They had a picnic lunch and then ran back for more fun in the creek. The water was only a foot deep, but too murky for them to see the bottom. Dylan’s tennis shoes squished down into the glop. All the boys were slipping around, but Dylan took a nastier slide. He wheeled his arms wildly to catch himself, lost the battle, and smacked down on his butt. His shorts were soaked instantly; dank black water splashed his clean T-shirt. Brooks and his brother, Aaron, howled; Dylan went ballistic.

“Stop!” he screamed. “Stop laughing at me! Stop! Stoooooooooooooooooooooooop! ”

The laughing ended abruptly. Brooks and Aaron were a little alarmed. They had never seen a kid freak out like that. Judy rushed over to comfort Dylan, but he was inconsolable. Everybody was silent now, but Dylan kept screaming for them to stop.

Sue grabbed him by the wrist and whisked him away. It took her several minutes to calm him down.

Sue Klebold had come to expect the outbursts. Over time, Judy did, too.

“I would see Dylan get frustrated with himself and go crazy,” she said. He would be docile for days or months, then the pain would boil over and some minor transgression would humiliate him. Judy figured he would grow out of it, but he never did.

Detectives assembled portraits of the killers that felt maddeningly similar and vanilla: youngest sons of comfortable, two-parent, two-child, quiet small-town families. The Klebolds had more money; the Harrises were more mobile. Each boy grew up in the shadow of a single older sibling: a bigger, taller, stronger brother. Eric and Dylan would eventually share the same hobbies, classes, job, friends, clothing choices, and clubs. But they had remarkably different interior lives. Dylan always saw himself as inferior. The anger and the loathing traveled inward. “He was taking it out on himself,” Judy Brown said.