BOSTON - Authorities have obtained clear images of the faces of two men with backpacks who they believe were acting suspiciously around the time of the Boston Marathon bombings, a potential breakthrough in the search to find who planted the bombs, sources familiar with the investigation said Wednesday.
A department store surveillance camera caught an image of at least one of the men leaving a backpack near the finish line, a federal law enforcement official said.
Another official briefed on the investigation said the image that shows two men is the first indication that more than one bomber may have been responsible for the attacks that killed three people and injured more than 170 at Monday's race.
The men drew attention because of their demeanor and the way in which they reacted to the blasts, said these officials, who could not be identified because they were not authorized to discuss the investigation publicly. Neither would say how close authorities were to identifying the two.
The photographic evidence adds to physical evidence already gathered at the scene, including parts of a pressure cooker probably used in the two bombs that went off as hundreds of runners were still streaming in five hours into the race.
Authorities are relying not only on extensive surveillance video but a flood of photos and videos sent in by spectators, office workers and others who were at the disaster scene.
"I think that this will go down … as the most videotaped bombing in history," said Tom Thurman, who formerly headed the FBI's Bomb Data Center and helped investigate the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, and the 1993 World Trade Center bombing.
President Obama was scheduled Thursday to speak at an interfaith service here for the victims, 59 of whom are still hospitalized, 10 in critical condition. The third victim killed has been identified as Lu Lingzi, 23, a Chinese national who was a Boston University graduate student in statistics.
Boston Mayor Thomas Menino and Massachusetts Gov. Deval Patrick said attorney Kenneth Feinberg would administer One Fund Boston, a fund set up to aid those affected by the attacks. Feinberg oversaw similar funds for victims of the Sept. 11 attacks and the 2010 BP oil spill.
The disclosures about the photos emerged on a day of conflicting reports in which a number of news agencies initially reported that a suspect had been identified and arrested and was scheduled for a court appearance.
Hundreds of reporters and spectators gathered outside the Joseph Moakley federal courthouse even as the FBI and Boston police denied anyone had been taken into custody.
Federal officials cautioned that building a case could take time.
"I think that this will go down … as the most videotaped bombing in history."
Formerly headed the FBI's Bomb Data Center