BOSTON -- In a direct appeal for help from the public, the FBI on Thursday released pictures and video of two young men who officials believe may be responsible for the explosions that killed three people and injured more than 170 during Monday's Boston Marathon.
Officials said they had images of one of the men putting a black backpack on the ground just minutes before two near-simultaneous blasts went off close to the race's finish line at 2:50 p.m. Officials said one video, which they did not release, showed the two men walking slowly away after a bomb exploded while the crowd fled.
At a news briefing in Boston, Richard DesLauriers, the special agent in charge of the FBI's field office in the city, initiated the unprecedented crowd-sourcing manhunt by urging the public to look at the pictures and video on the FBI's website. The two men appear to be in their 20s, but Mr. DesLauriers did not characterize the appearance of the men or offer an opinion as to their possible ethnicity or national origin.
>The photos put faces on suspected perpetrators whose identify and whereabouts have been the subject of endless, often-erroneous speculation since Monday's remotely detonated blasts.
But the imagery, while it seemed to rule out a lone wolf, did not answer whether the bombing was a terrorist attack associated with a foreign or domestic extremist group, or whether there was another unknown agenda.
The man whom the FBI identified as "suspect No. 1" was not captured on video dropping his backpack, Mr. DesLauriers said. He wore dark glasses, a black baseball hat pulled low, chino pants, a white T-shirt and a dark jacket.
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 Mr. 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 Mr. DesLauriers said they appeared to investigators to be associated with each other.
Mr. 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 instead to immediately call the FBI or local police. "Do not take any action on your own," he said.
Law enforcement officials hope that 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 prospect of another bombing while the two remain at large.
Word of a break in the story caused about 120 reporters and photographers to hurry to a Sheraton hotel not far from the marathon finish line for the 5 p.m. FBI briefing. Bomb-sniffing dogs outside a third-floor ballroom checked everyone's bags. Journalist and officials barely fit in the ballroom, along with two dozen television cameras.
Still images were displayed on two large black easels. One poster showed four images of the suspect with the black cap, and the other displayed four of the suspect in the white cap.
While the still and video images were slightly blurred, experts said they will help investigators determine the height, weight and body types of the suspects.
"Somebody out there knows these individuals as friends, neighbors, co-workers or family members of the suspects," Mr. DesLauriers said firmly and grimly into the cameras. "Though it may be difficult, the nation is counting on those with information to come forward and provide it to us."
Almost immediately, calls started flooding the bureau's office complex in Clarksburg, W.Va. Traffic to the FBI website spiked to the highest levels it has ever received, one official said. For a brief period of time, the website was offline.
Typically, about two dozen analysts sitting in cubicles there answer calls 24 hours a day, seven days a week. But in the days after Monday's attacks, the center was inundated with calls, and it has since increased the numbers of analysts and agents, according to a law enforcement official.
Attorney General Eric H. Holder Jr. and FBI Director Robert S. Mueller III were directly involved in the decision to release the photos, a senior law enforcement official said.
Michael R. Bouchard, a former assistant director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, said that in releasing the photographs and video, authorities had taken a calculated risk. "If you don't release the photos, the bad guys don't know you're on to them while you're looking," said Mr. Bouchard, who helped oversee the Washington, D.C., sniper case in 2002 and now runs his own security consultancy in Vienna, Va. "If you do release them, you run the risk they see them and change their appearance or go underground. They made a calculated decision. The benefits of releasing the photos outweighed the risks of holding back and trying to identify them themselves."
Mr. Bouchard said several characteristics in the images selected for release were distinctive: the emblem on one man's hat, the backpacks they carried, their gaits and the sight of the two men walking together.
"They don't know if these guys are from out of town, so they had to cast their net wider," said Mr. Bouchard, who said widespread use of social media and cellphones made such identifications easier than just a few years ago. "Now, the public becomes a force multiplier."
Mr. DesLauriers did not specify what led the FBI to call the two men suspects, but the official said that decision was "based on what they do in the rest of the video." The official said: "We have a lot more video than what we released. The sole purpose of what we released was to show the public what they looked like. The other videos show other things."
One law enforcement official said the suspects in the photographs had captured authorities' interest because of their bags. Crime scene investigators recovered portions of a shredded black backpack that they believe carried explosives, this official said, and they were able to determine the brand and model of the bag. The backpack carried by at least one of the men in the videos appeared to be a match, the person said.
The fact that FBI officials chose to make the video images public suggested to some people familiar with law enforcement tactics that they have not been able to match them with faces in government photo databases, said Jim Albers, senior vice president at MorphoTrust USA, which supplies facial recognition technology to the government. The FBI has a collection of mug shots of more than 12 million people, mostly arrest photos. "The only conclusion you can reach is that they don't have a match they have confidence in," Mr. Albers said.
That could be a question of the quality of the images of the two suspects -- the video footage posted by the bureau does not include high-resolution, frontal images of the two men's faces, as would be ideal for facial recognition software, Mr. Albers said. Or it may be that the search software, which produces a list of matches ranked by probability, simply did not find a persuasive match.
The pictures made public Thursday night are "a digital wanted poster," an update of the traditional tool used at post offices for decades, Mr. Albers said. "Cops have been using facial recognition since there have been cops. They just didn't have technology to help them."
The Washington Post contributed. First Published April 19, 2013 4:00 AM