The pressure-cooker type bombs authorities say were used in Monday’s deadly attack were crude but common methods of attack used by terrorists in Afghanistan, said Todd Sartain, who now investigates IEDs for a military contractor in that war-torn country.
Sartain left the Athens-Clarke police Forensics Unit in 2008 to work in Iraq, and has been in Afghanistan the past three years.
From the 400 or so IEDs he’s examined, Sartain knows that certain groups make bombs in specific ways, effectively leaving their signatures.
“It’s kind of like how you can identify burglars because of the way they break into homes, the things they take and what they leave behind,” Sartain said. “It’s the same way with a bomb maker, who will twist wires to the left or the right, use certain types of chemicals, detonation devices, etc.”
No one claimed responsibility for the marathon bombing, and authorities had not said if they suspected any individuals or groups.
Authorities did say the explosive devices were fashioned out of pressure cookers packed with nails, ball bearings and other material to inflict maximum carnage.
“I saw one bomb in Afghanistan that was made with a pressure cooker that looked just like one my grandmother used,” Sartain said.
It was widely reported on Tuesday that a Department of Homeland Security memo called it a technique commonly taught in Afghan terrorist training camps.
“Typically, these bombs are made by placing TNT or other explosives in a pressure cooker and attaching a blasting cap at the top of the pressure cooker,” the memo reportedly noted.
After the blasts Monday, officials reported that suspicious packages were detonated out of precaution, but on Tuesday they said the two bombs that exploded near the marathon’s finish line were the only explosive devices used in the attack that killed three people and injured more than 170.
Sartain said the job of those investigating the bombing would have been made easier it an intact device was located, but experts will be able to reconstruct the bombs from fragments and components recovered at the blast sites.
They also will have more time to gather and analyze evidence with the hope of identifying who was responsible for the bombings.
“It’s a little different working a scene here than it is overseas because it’s a criminal justice matter, not for intelligence,” Sartain said. “When we get evidence from an IED in Afghanistan, we process it within 24 hours to get information back out to the troops as quickly as we can before there’s another attack.”