Photographs by John B. Carnett: Burn patterns left by the accelerant tip students off to arson; forensic anthropologist Joanne Devlin in firefighting regalia. Photographs by John B. Carnett

A morning mist clings to the foothills as 15 crime scene investigators from across the country approach a shrapnel-pierced Pontiac Bonneville outside Knoxville, Tennessee. Minutes before, a fiery blast engulfed the car's passenger area, exploding the side windows and sending the crazed-glass windshield arcing, slo-mo, 50 feet through the air.




Scene commander Tom Sparks, a beefy lieutenant with the Hartselle, Alabama, police department, designates a sketch artist and photographer to record the vehicle exactly as found and assigns five more CSIs the task of dismantling it for evidence regarding the cause of the blast. Another seven line up with Sparks along one side of the scene perimeter. "Step," he bellows. They move one stride forward before bending to mark potential clues. Within minutes, the sodden ground blossoms with orange evidence flags.




Back at the Bonneville, Joy Smith, a tall, blonde evidence specialist from Modesto, California, peers into the red-clay hole where the passenger seat and floorboard had been. She searches for anything remotely bomb-like in the surrounding jumble of shredded wiring, metal and plastic. "Now I see the wisdom of spending time at Radio Shack," she says. "It all looks like car parts to me."




Thirty minutes into the investigation, crucial clues emerge. From inside the passenger door a team member pulls a chunk of galvanized steel with threads on one side and the raised imprint "1 1/4" on the other. "Looks like we've got a 1 1/4-inch pipe," he says. Others pull matching bits of steel shrapnel from the perforated headliner. A cobalt-blue sheen marks the shorn edges
of several pieces—the signature of a high-power explosive.




From the shredded driver's seat, Ohio crime technician Matt Dulaney digs out a curl of flattened metal and holds it to his nose. "Gunpowder," he says. "Doesn't a windup clock have a round spring?" The perimeter searchers, for their part, have found shreds of duct tape that, all agree, could have held a pipe bomb and detonator together. The CSIs confront a grizzled former Marine turned explosive ordnance expert. "Very good," he says, nodding. "I put a pound of C4 in the pipe, used a clock timer, and shoved it all under the passenger-side seat."




Time to move on: Knoxville bomb-squad commander Van J. Bubel has other surprises in store this morning. He directs the group's attention to a shoe bomb laced to the elegantly turned foot of a fashion mannequin standing across the field.




"She's just like that guy on the airplane," says Bubel, a detonator cord in hand, "only smarter."




Ka-boom.