BOSTON (CBS) – FBI agents looked at nearly 13,000 videos and more than 120,000 photographs before finding the one video clip that eventually led them to the Boston Marathon bombing suspects.
Those are new details from a "60 Minutes" report from CBS Evening News anchor Scott Pelley that takes an unprecedented look at the investigation.
The FBI scanned video recorded on dozens of surveillance cameras up and down Boylston Street after the bombing on April 15.
"Almost 13,000 different videos were obtained, (and) more than 120,000 still photographs," Stephanie Douglas, Former FBI Executive Assistant Director, told Pelley.
One-hundred-twenty analysts searched video feeds from Boston at the FBI lab in Virginia.
Pelley said the 'Eureka' moment came Wednesday, two days after the bombings.
"A photo analyst in Boston going through the video again and again and again, noticed this video that has not been seen in public, in which the first bomb goes off. You don't see that, but everybody in the shot in the video looks suddenly to their left in shock and surprise, except one guy. He doesn't look, doesn't turn around, isn't surprised and he walks away," Pelley told CBS This Morning Friday."
"And earlier in that video he had placed a backpack on the ground. Twenty seconds after he walks out of the frame, the backpack explodes, killing an eight year-old boy (Martin Richard), taking the leg from his seven-year-old sister and wounding many other people right there around that backpack."
Pelley said he was told the video is horrific and is not likely to be seen by anyone until Dzhokhar Tsarnaev's trial.
Douglas told him it also shows a man with his clothes on fire. "A police officer leaps on him and puts the fire out with his bare hands, with no concern for his own safety," Pelley said.
"They literally watched it 400 times to make sure they understood what was going on. But it took a toll on everyone, including the director of the FBI when they saw it."
Pelley said he was amazed that the FBI had at least 1,000 agents and analysts working on the case "all at once, which is how they were able to solve this in just 101 hours."
You can watch the full report on "60 Minutes' Sunday night on WBZ-TV.
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