WASHINGTON — The bomb investigators swarming Boston are combining high-tech tools with old-fashioned shoe leather as they piece together what blew up and why.
A special federal bomb squad has mobilized, joining state and local counterparts in a search for everything from the shrapnel that slashed victims to the blast residue left behind after dual blasts Monday killed three and injured more than 170 near the finish line of the Boston Marathon. It’s painstaking work, combining chemistry, computer databases and sheer doggedness.
Richard DesLauriers, special agent in charge of the bureau’s Boston division, appealed to the public late Tuesday to produce any information about anyone seen carrying a dark heavy bag at the scene of the bombing or who threatened an attack on the Boston Marathon. He also sought information about explosions heard in remote areas where the bomber might have conducted tests.
“We are doing this methodically, carefully, yet with a sense of urgency,” he said. “Someone knows who did this. Cooperation from the community will play a crucial role in this investigation.”
Gene Marquez, acting special agent-in-charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives’ Boston field office, said that the bombing scene would take “several days to process.”
Some clues come from what doctors pull from the victims’ bodies. Doctors on Tuesday reported that they have been extracting objects including pellets and nails from the legs and torsos of victims, a sign that the two bombs that exploded Monday had been destructively packed.
A former senior U.S. government official who was briefed on the investigation confirmed for McClatchy that the bomb was put into a pressure cooker, a tactic counterterrorism agencies have found in the past in jihadist plans and “recipes.”
No one has claimed credit for the bombings.
Following an Oval Office meeting Tuesday with President Barack Obama and his top national security advisers, Homeland Security Secretary Janet Napolitano said there was no evidence that the bombings were part of a broader scheme.
Among the lines of inquiry are that the attack was the work of domestic terrorists or a lone wolf, said a person familiar with the investigation,.
The Boston Globe reported midafternoon Tuesday that investigators had found a circuit board believed to have been used in the detonation of the bombs.