Investigators combing through the grim aftermath of the deadly Boston Marathon terrorist attack have found evidence that timing devices were used Monday to detonate the bombs that ripped through race spectators on Boylston Street, said an official briefed on the investigation.
Working with fragments painstakingly gathered at what is considered the city’s largest-ever crime scene, they also determined that the two bombs were probably fashioned from 6-liter pressure cookers, filled with nails and small ball bearings, like buckshot, to increase the carnage, and then hidden in black nylon bags or backpacks and left on the ground. FBI bomb experts at the FBI Academy in Quantico, Va., will try to rebuild the devices from fragments that include a circuit board that indicated the bombs were detonated on a timer, rather than remote control.
The bombs, which detonated 12 seconds apart just after 2:50 p.m. Monday near the finish line of the world’s most prestigious road race, killed three people, injured 176 others, and set an entire city on edge.
Extra police patrols roamed eerily quiet streets on Tuesday. Security fears disrupted two flights at Logan Airport, as airlines responded to the concerns of jittery passengers. And the White House confirmed that President Obama would visit the city on Thursday, to speak at an interfaith prayer service.
The FBI, which is leading the massive investigation into the bombing, asked the public for tips on anyone who may have been lugging a heavy black bag near the finish line. Local and federal law enforcement officials are scouring thousands of photographs and video for some sign of the bomber.
“The person who did this was someone’s friend, co-worker or neighbor,” said Richard DesLauriers, special agent in charge of the FBI’s Boston office. “Somebody knows who did this.” No one has claimed responsibility for the atrocity and the investigation remains “wide open,” DesLauriers said.
As the investigation broadened, so did the city’s mourning, as more details were revealed on the three people who died — an 8-year-old boy from Dorchester, a 29-year-old woman from Medford, and a Chinese graduate student at Boston University — and the scores injured, many of whom lost limbs.
Bostonians shaken by the attack woke Tuesday to a changed city, with heavily armed officers standing sentry at intersections, MBTA stations, the airport and even city parks.
But there also were moving displays of solidarity from cities across the United States: The Boston city flag flew at half-staff at New York City Hall in Manhattan. The Chicago Tribune sports section published a tribute to Boston sports teams. “As much as it is anathema for a Chicago fan to root for any other town — especially Beantown and all of its championships — here we are,” the paper wrote. “Hang in there, Boston.”
And at Yankee Stadium in the Bronx, Boston’s ultimate rival displayed the Yankee logo side-by-side with the Boston Red Sox “B” and the message: “United We Stand.”
And in the city, words of caution mixed with defiant optimism. “We’re Boston; we’re one community,” said Mayor Thomas M. Menino. “We’re not going to let terrorists take over our city.”
During briefings, Governor Deval Patrick announced that the interfaith prayer service, which Obama will attend, had been scheduled for 11 a.m. at the Cathedral of the Holy Cross.
According to the official briefed on the investigation, the first of the two bombs to explode was placed on the ground on Boylston Street, across from finish-line viewing stands where dignitaries had been sitting earlier, including Patrick; the second bag was placed on the ground about 75 to 100 yards away, outside the Forum restaurant at 755 Boylston St.
The bomb-making technique used in the attack was detailed in a 2010 article in the online magazine, Inspire, published by the terrorist group Al Qaeda. The technique was used in the attempted bombing of Times Square in 2010, as well as in an attack in Pakistan earlier that year.
However, security experts said the technique is akin to a scaled-up pipe bomb, and has been used in attacks by organizations not related to Al Qaeda.
Roy Parker, a retired Bureau of Alcohol, Tobacco, Firearms, and Explosives agent who developed the agency’s explosives training program, said Tuesday the circuit board would be “ key to determining whether it was a timer or remote control device.”
Based on his past experience investigating some 50 bombings, Parker said examiners are looking at scraps of the bomb components, bags and all forensic evidence found at the scene of the blasts. “You’re looking for a needle in a haystack, but the needle is there,” said Parker, who now works for TWT Consulting in Maryland. “If you look long enough, you’ll get stuck with it. This is not an unsolvable crime.”Continued...