Associated Press
David Green's cell-phone photo of Dzhokhar Tsarnaev appearing to move away from the scene of last Monday's bombing almost seemed too good to be true, Associated Press Director of Photography Santiago Lyon said in a phone call Friday evening.

"When the picture began to circulate, we were suspicious of it because when we looked at it closely it seemed to have been a composite picture," Lyon said. "But what happens often with digital imagery is when you're looking closely at low-resolution files you see things that are misleading, because of the way the pic is compressed or the size of the file."

A cropped version of Green's photo (AP Photo/David Green)

So the AP asked Green, a Florida businessman who'd completed the marathon and was watching other runners finish when the bombs went off, for a high-resolution version of his pic. The time stamp and the resolution convinced the photo department it was real. After the AP did a little reporting on Green -- making sure he'd run the race, that he was who he said -- they struck a licensing deal.

Such Cinderella stories used to be rare -- for example, the Texas doctor who captured a shot of Space Shuttle Columbia breaking apart -- but the AP is increasingly looking for eyewitness content, Lyon said.

The news coop will "find the images on the Web and social media and other places," he said, "and then we track down the photographer." There's no team dedicated to the task, Lyon said, but a couple of photo staffers will draw duty, especially after a dramatic event.

Green's friend Jason Lubin told the AP he spotted Tsarnaev, in his now-famous white baseball cap, when he looked closely at his friend's photo. "I literally had to sit down," Lubin told the service.

Other photo news from last week's bombings and manhunt:

• Bloomberg photographer Kelvin Ma on his photo of bombing victim Jeff Bauman, who later helped identify the suspects: "as a professional witness, I don’t know how else to show not only the evil of the world, but also the compassion and humanity that ultimately overcomes it."

• Seattle runner Bill Iffrig didn't see John Tlumacki's now-iconic shot of him on the ground after one of the explosions until he was flying home on Friday, when an airline employee gave him a copy of Sports Illustrated, which fronted it. "It’s almost like it was staged, it’s so real," Iffrig said. (Here's a interview with Boston Globe photographer John Tlumacki, who took the photo of Iffrig.)

• Massachusetts State Police released thermal-imaging photos taken from a helicopter that show Tsarnaev sheltering in a boat in Watertown, Mass.