Just hours after the FBI released the first photos of suspects in the Boston Marathon bombing, a new photo of Suspect 2 emerged.

UPDATE: Dzhokhar Tsarnaev, 19, was captured on Friday in Watertown, Mass. Read more about his apprehension here.

EARLIER:

David Green, 49, of Jacksonville, Fla., had just completed his first Boston Marathon, when he snapped a picture with his iPhone 4S, taken at 2:50, just after the two blasts ripped through the finish line area, killing three people and injuring more than 180 others.

The FBI has not publicly confirmed this photo as Suspect 2, but Green told the Huffington Post that an agent told him, "this is probably the best we have right now." The Associated Press has also authenticated the photo.

The man who appears to be Suspect 2 is wearing a white hat with a "3" on the side as seen in the publicly-released photos.

new photo suspect 2

After finishing the marathon, Green said he collected his belongings, and planned to meet with friends near the finish line. Then a pair of bombs exploded.

"The second bomb went off right in front of me," Green said in an interview with The Huffington Post.

One of his first instincts was to get a quick photo. Then he proceeded toward the victims to try to help. That photo can be seen above.

"I soon realized there was nothing I could do but step back," he said. "I couldn't believe what I was seeing [...] I saw people lying in the streets, it was complete mayhem."

It was the only photo he took, he said. Then he started to get some video of the scene.

Green posted the photo to Facebook on Monday.

Little did he know that a man shown in his photo could be one of the men now wanted by the FBI. In the photo, the man seems to be walking away from the scene and he appears to have no backpack.

"This speaks to the power of social media," Green said this evening. "A friend reached out to me and said look at your photo, that's definitely the guy."

Green got in touch with the FBI tonight and said he spoke with multiple agents. He specifically asked if they were OK with him publishing the photo publicly to his Facebook page and he was told it was fine. So he posted it again.

He wrote in the photo caption to family and friends, which he said he knowingly posted publicly so others could see:

Friends & Family,

I have been feeling down since the Boston Marathon bombing because I couldn't do anything to help the injured victims...until now. Thanks to my friend Jason who pointed out to me that the photo I took right after the second bomb and posted on FB has suspect #2 in the left hand corner of the photo. White baseball cap turned backwards, black sweatshirt, NO BACKPACK right after the bomb went off. Compare to the ones posted by CNN, it is unmistakable. I spoke to the FBI and it is may be the best photo they have at current time!!! One step closer to taking these @!#?#'s down...share as much as you can so that if someone knows this person they can turn them in.

The post has gone viral with more than 5,000 shares in a few hours and it has since skyrocketed to more than 12,000 shares.

The photo started getting attention on Reddit around 8 p.m. ET. A debate emerged whether it was digitally-altered or not.

Green's original post on Facebook, time-stamped Monday before the FBI released any photos, showed that it was not.

According to The New York Times, Green did not originally notice the man in the white hat, but he instead called the FBI earlier in the week to report another man, "who was standing still and yelling instead of running."

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  • Suspects 1 and 2

  • This frame grab from a video released by the FBI on Thursday, April 18, 2013, shows what the FBI are calling suspect number 1, front, in black cap, and suspect number 2, in white cap, back right, walking near each other through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • Suspects 1 and 2

  • Suspect 1

  • Suspect 1

  • Suspect 1

  • Suspect 2

  • This image from video released Thursday, April 19, 2013 by the FBI shows one of two suspects sought in connection with the Boston Marathon bombings. (AP Photo/FBI)

  • Suspect 2

  • This combination of Associated Press file images released by the FBI on Thursday, April 18, 2013, show two images taken from surveillance video of what the FBI are calling suspect number 2, left, in white cap,and suspect number 1, right, in black cap, as they walk near each other through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI, File)

  • This frame grab from a video released by the FBI on Thursday, April 18, 2013, shows what the FBI are calling suspect number 1, black cap in lower right, walking in front of suspect number 2, not seen, through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • This frame grab from a video released by the FBI on Thursday, April 18, 2013, shows what the FBI are calling suspect number 1, black cap with backpack, walking in front of suspect number 2, white cap at lower right, through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • Suspect 2

  • This image from video released Thursday, April 18, 2013 by the FBI shows one of two suspects sought in connection with the Boston Marathon bombings. The FBI released photos and video of the two suspects and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack. (AP Photo/FBI)

  • Suspect 2, Hand Next To Ear

  • This image from video released Thursday, April 18, 2013 by the FBI shows one of two suspects sought in connection with the Boston Marathon bombings. The FBI released photos and video of two suspects in the Boston Marathon bombing and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack. (AP Photo/FBI)

  • Suspect 2

  • This image from video released Thursday, April 18, 2013 by the FBI shows one of two suspects sought in connection with the Boston Marathon bombings. The FBI released photos and video of two suspects in the Boston Marathon bombing and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack. (AP Photo/FBI)

  • Boston Marathon Explosions

    This image provided by the Boston Regional Intelligence Center shows Dzhokhar A. Tsarnaev, one of the suspects in the Boston Marathon bombings. Authorities say Tsarnaev is still at large after he and another suspect — both identified to The Associated Press as coming from the Russian region near Chechnya — killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt in a long night of violence into the early hours of Friday, April 19, 2013. The second suspect, who has not yet been identified, was killed in a shootout with police. (AP Photo/Boston Regional Intelligence Center)

  • This surveillance photo released via Twitter Friday, April 19, 2013 by the Boston Police Department shows a suspect entering a convenience store that police are pursuing in Watertown, Mass. Police say he is one of two suspects in the fatal shooting of an MIT police officer and tied to the Boston Marathon bombing. (AP Photo/Boston Police Department)

  • MIT SHOOTINGS 2

    Graphic shows photos of suspects; locates Watertown and Cambridge, Mass., where Boston Marathon bombing suspects exchanged gunfire and one is dead

  • This combo of photos released by the FBI early Friday April 19, 2013, shows what the FBI is calling suspects number 1, left, and suspect number 2, right, walking through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • This photo released by the FBI early Friday April 19, 2013, shows what the FBI is calling suspect number 1, walking through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • This photo released by the FBI early Friday April 19, 2013, shows what the FBI is calling suspect number 2, walking through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • This photo released by the FBI early Friday April 19, 2013, shows what the FBI is calling suspect number 2 behind a lady, walking through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • This photo released by the FBI early Friday April 19, 2013, shows what the FBI is calling the suspects together, walking through the crowd in Boston on Monday, April 15, 2013, before the explosions at the Boston Marathon. (AP Photo/FBI)

  • BOSTON MARATHON

    Graphic shows photos of the suspects and where they were caught on tape, a demographic profile of the runners and a map of the marathon path

  • Screen shot 2013-04-19 at 14

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston, Mass. These images show what is believed to be Boston bomber Tamerlan Tsarnaev boxing at the Wai Kru Mixed Martial Arts center in Boston, MA. The native Chechnya, dubbed Suspect 1 by the FBI, and has been reported as dead. He was described as a heavyweight fighter at the gym, and allegedly hoped to fight for the U.S., because his home nation was not recognised in the sporting world.

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston, Mass.

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston.

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston.

  • Tamerlan Tsarnaev

    Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston.

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston.

  • Tamerlan Tsarnaev practices boxing at the Wai Kru Mixed Martial Arts center in April 2009 in Boston.

  • Tamerlan Tsarnaev