attack but he pledged his full support to the fbi bosses even as old rivalries and jealousies between the locals and the feds were hardly forgotten for most of the day the fbi worked on the theory that the bomber or bombers might be among those injured and agents were stationed at the area hospitals to keep order but also to make sure none of the injured could leave managing a crisis requires communication and for hours the fbi cell phones did not work because so many in boston were trying to call loved ones to make matters worse the fbi makeshift forward command center in a ballroom of the westin hotel had only one hardwire phone which fbi special agent in charge rick deslauriers commandeered so he could talk to washington this is mine he shouted as others tried to steal it away to call their own bosses hundreds of fbi agents from around the country were sent into the city for the first few hours there was no effective way to reach them or hand out assignments nor was there any place for them to sleep many simply slept in their cars in the fbi garage several agents ended up in the hospital from exhaustion including the fbi official designated to handle crisis situations in boston agents worried there were more bombs in the hundreds of backpacks and purses left behind as spectators ran for cover so each and every piece had to first be examined by a bomb squad before being collected the fbi immediately created a giant evidence processing center at a warehouse on boston harbor called black falcon the crime scene was divided into hundreds of grids and every tiny piece of evidence was recorded with a gps device to show precisely where it was recovered according to agents involved in the investigation twice a day fbi airplanes flew pieces of evidence to the fbi crime laboratory in quantico virginia this combination of april 15 2013 and april 10 2014 photos show a view of boylston street in front of the forum restaurant where investigators comb for eviden show more elise amendolaap photo first key clues bomb fragments surveillance images within hours agents had a vital piece of evidence the bottom of one of the pressure cookers converted into a lethal bomb it was found on the roof of a hotel on the race route blasted 100 feet in the air by the power of the bomb stamped into the piece was the name of the fagor company the european company that manufactured the pressure cooker a squad of fbi agents was assigned to do nothing else but track every single pressure cooker shipped by the european company which would eventually lead them to purchases made in the boston area a photograph of a piece of one of the boston marathon bombs taken as evidence fbi as investigators raced to trace clues in the bombs history a large team of agents worked from the other