CHICAGO (CBS) — Was Adam Toledo holding a gun when a police officer shot and killed him last month? It’s a key question as the Civilian Office of Police Accountability continues to investigate the shooting after releasing video footage and other materials on Thursday.

CBS 2’s Tara Molina spoke to experts who honed in on the few seconds just before the officer opened fire.

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The video is 9 minutes and 22 seconds long. The shooting happens in the first 2 minutes and 5 seconds.

The first minute and 40 seconds just shows Officer Eric Stillman driving, dispatched to a ShotSpotter alert of eight gunshots in Little Village.

One minute and 44 seconds into the video, Stillman gets out of his car, immediately running down the alley near 24th and Sawyer.

His body camera video shows Adam Toledo running down the alley in a white hat, along with 21-year-old Ruben Roman, wearing a gold jacket.

The video shows Roman get pushed to ground, and Stillman continuing to chase Adam, who keeps running down the alley.

You don’t hear any sound until 1 minute and 58 seconds into the video, when the officer shouts at Adam to put up his hands.

The video shows Adam near the opening in a fence in the alley, both hands at his sides, his left shoulder facing the officer. The boy then starts to turn to fully face the officer.

That is the moment Arthur Lurigio, a professor at Loyola University and criminologist with a background in deadly use of force, focused in on Thursday.

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“The barrel of the gun was shining,” Lurigio said.

He is talking about the moment the video clearly shows something in Adam’s hand.

“You need to look repeatedly at the video, and you need to freeze the frame. It appears that the young boy has a gun in his right hand. You have to look at it repeatedly to see that,” he said.

Lurigio said Adam assumed a position that suggested he might have gone on to toss the gun.

“His right hand appeared to be in a position where he could’ve dropped it or thrown it behind the fence where it was found,” Lurigio said.

Stillman shot Adam one time as the boy was raising his hands, and immediately radioed in a report of shots fired and a request for medical help.

Then Stillman tried to revive Adam, and other officers came in to help. After a few moments of trying to perform CPR, Stillman stood up and started pacing around as other officers kept trying to revive the boy.

Less than three minutes after shooting Adam, the officer shone his flashlight on a handgun on the ground on the other side of the fence, just feet away from where the boy fell after he was shot.

Lurigio suggested that anyone who chooses to view the video watch it closely. Keep in mind this was a fast moving situation, and there was an assumed threat, because there were shots fired just a minute before officers arrived on the scene.

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“We are really talking about a second, which is real time is not going to be the same as the second I’m experiencing when I’m pausing the video, viewing it. Rewinding. Reviewing and viewing,” he said. “It is literally a second.”

Tara Molina