BOSTON - The FBI released video and photos on Thursday of two suspects in the Boston Marathon bombings who were seen carrying backpacks and walking casually among spectators shortly before the blasts.
Officials hope the release of images culled from a trove of digital information will help them identify and capture the men who were described by Richard DesLauriers, special agent in charge of the FBI's Boston division, as "armed and extremely dangerous."
DesLauriers said at a Boston press conference that investigators first identified one person of interest in the last day and that breakthrough led to a second. He appealed for the public's help in identifying the men.
The photos put faces on suspected perpetrators whose identify and whereabouts have been the subject of endless, often erroneous speculation since the remotely detonated bombs killed three and injured 176 near the race finish line Monday.
But the imagery released by the FBI , while it seemed to rule out a lone wolf, did not answer the question as to whether the bombing was a terrorist attack associated with a foreign or domestic extremist group or whether there was another unknown agenda.
The man who was identified by the FBI as "suspect No. 1" was not captured on video dropping his backpack. He wore dark glasses, a black baseball hat pulled low, chino pants, a white T-shirt and a dark jacket. DesLauriers said he was not captured on video dropping the black backpack he was carrying.
The second man, wearing a white baseball hat backwards and dark clothing and carrying a light-colored backpack, was taped setting down what the FBI believes was the bomb that caused the second blast outside the Forum restaurant on Boylston Street near the finish line. The man then proceeded west on Boylston.
The well-known restaurant was hosting a race-watching party at the time, and DesLauriers appealed to people who were there and who have not yet come forward to contact the FBI.
Both suspects looked like any other visitor to the city on marathon day. In the snippets of released video, they appeared unhurried as they moved along the street. The video showed both men walking in single file in close proximity on Boylston Street shortly before the explosions, and DesLauriers said they appeared to investigators to be associated with each other.
"Somebody out there knows these individuals," said DesLauriers. He said the video and photos were posted on the the FBI website, www.fbi.gov.
DesLauriers said locating the suspects was the "highest priority" of investigators, but he cautioned the public not to attempt to attempt to confront or apprehend them and immediately call the FBI or local police. "Do not take any action on your own," he said.
Law enforcement officials hope the photos will be seen worldwide. In the three days since the bombing, the suspects may have left the Boston area and could well have left the country, said a law enforcement official who spoke anonymously because he was not authorized to discuss the case publicly.
The official said the FBI is also concerned about the possibility of another bombing while the two men remain at large.