UPPER MARLBORO, Md. (WJZ) — Prosecutors begin their case against two Prince George’s County police officers caught on camera repeatedly hitting a University of Maryland student as crowds gathered in the streets of College Park after the Maryland/Duke basketball game in 2010.

Derek Valcourt has more on the case that all started with that dramatic video.

Monday, prosecutors and defense attorneys are trying to paint two very different versions of what that now infamous video shows.

Prosecutors say Officers Reginald Baker and James Harrison can be seen in the video taking unarmed Maryland student John “Jack” McKenna to the ground and repeatedly beating him with their batons, calling it an unnecessary use of force.

Their first witness was Baltimore resident and former Maryland student Nathan Cole, who saw it all.

“I lost sleep over it. It sickened me to see an innocent kid like that get beat to that amount,” Cole said.

Cole shot his own cell phone video, which shows an even closer angle of what happened. It’s now key evidence in the trial.

“This kid had no threatening stance, no threatening manner, didn’t threaten the cops. Next thing you know, he’s blindsided, his head slammed into the wall and ends up on the ground and gets beat several more times,” Cole said. “That’s someone’s son. If that was my brother, I’d be infuriated. So I was compelled to come here and tell what actually happened.”

But the defense attorneys say the man getting beaten in this video was the aggressor who threatened the officers. They argue he even fought back and that, they say, justifies their use of force.

Late Monday, McKenna took the stand. He told the jury because of the large crowd in the street, he didn’t see the police until he was right near them. That’s when he says he put his hands up to surrender. He says because of his head injuries, he doesn’t remember all the details of the beating. He admitted he had been drinking five to six beers with his friends that night.

The officers face assault charges and misconduct in office.

The jury is expected to have the case by the end of the week.