BOSTON – Before the bombs went off Monday, a young man in a white baseball cap and dark jacket dropped his backpack outside a restaurant on Boylston Street. He then turned and walked west, away from the finish line and in the opposite direction of runners jogging the final yards of the Boston Marathon.
Investigators offered limited details of the movements of one of the two suspects whose photographs the FBI released Thursday in the first major break in the Boston Marathon bomb case.
The photographs show a second suspect, a young man in a dark hat and jacket, also carrying a backpack. Investigators believe that the bombers used backpacks to conceal pressure cookers packed with explosives that they planted outside the restaurant and at a site one block away. Together, they killed three spectators and injured more than 170 on Monday afternoon.
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Investigators released the pictures and a surveillance video of the suspects, walking one after the other a few feet apart, captured at 2:37 p.m., about 13 minutes before the explosions. Each is still carrying his backpack.
In the video, the suspects appear to turn from a side street east onto Boylston, walking toward the finish line past spectators lined up behind metal barricades. From there, they would have had to walk just a couple of blocks to the sites where the explosions occurred.
FBI Special Agent in Charge Richard DesLauriers said the bureau was asking for the public’s help in identifying the two suspects by calling in tips to (800) CALL-FBI, or (800) 225-5324.
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“We consider them to be armed and extremely dangerous,” DesLauriers said at a packed news conference Thursday afternoon, adding that members of the public should not approach them.
DesLauriers said the FBI was seeking additional images captured by customers at the Forum restaurant, the site of the second blast, where the suspect in the white cap put down his backpack. “No bit of information is too small,” he said.
Law enforcement agencies have received 3,000 images in addition to surveillance videos and TV news footage, which added up to several terabytes of data, investigators said. The images were plugged into facial recognition software programs and pored over by a team that includes more than 1,000 Massachusetts and federal law enforcement agents.
Within the last two days, investigators identified one “person of interest” in the case, DesLauriers said. They went back over the images and data to determine whether that person was alone or with others, leading to the identification of the second suspect. It was unclear when the breakthrough came; as early as midday Thursday, officials said they hadn’t decided whether to release images to the public.
“It was a combination of technology and hard work,” said FBI spokesman Jason Pack.
The FBI also has found what its investigators believe to be the detonation system for the bombs: a circuit board and parts from a toy remote control vehicle, a counter-terrorism official said.
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The release of the pictures of men identified by the FBI as suspects came as Boston rallied in an interfaith commemoration of the victims at the Roman Catholic Cathedral of the Holy Cross, where speaker after speaker pleaded with Bostonians to summon their stubborn spirit as the region recovers. Among the speakers were President Obama, Gov. Deval Patrick and Boston Mayor Thomas Menino.
“Boston is the perfect state of grace,” said the president, quoting a poetic description of the city that was torn by the blasts. “In an instant the day’s beauty was shattered. A celebration became a tragedy.
“And so we come together to pray and mourn and measure our loss,” Obama said. “But we also come together today to reclaim that state of grace. To reaffirm that the spirit of this city is undaunted and the spirit of the country shall remain undimmed.”