By Dave Savini, Samah Assad, Michele Youngerman

CHICAGO (CBS) — The man who was body slammed by a Chicago cop said he was not resisting arrest in his first one-on-one interview since the incident.

Bernard Kersh, 29, accused Officer Jerald Williams of excessive force when Williams lifted him into the air and slammed his head to the cement curb on Thanksgiving.

“He picked me off my feet and slammed me head first into the concrete,” Kersh said in an interview with CBS 2. “I could have been killed.”

The viral video was originally captured on a cell phone and posted to social media. But CBS 2 has obtained new footage from two different security cameras. It shows different angles and about five minutes leading up to the body slam.

Police said officers stopped Kersh to give him a ticket when they saw him drinking alcohol in plain view at a bus stop. They said he resisted arrest, and spat at and licked Williams’ face. Kersh denies it.

“I didn’t spit at no officer,” he said. “I don’t lick no officer’s face.”

In the security footage, Kersh is seen motioning toward Williams right before the takedown, but it’s unclear in the video if he licked or spit at him. Williams can be seen wiping his face after slamming Kersh.

Kersh said when he hit the curb, he “blanked out” and was knocked unconscious.

“Everything went black,” he said.

The security video first shows a white police SUV pull up to a bus stop. Williams gets out of the vehicle, goes into the bus shelter and grabs Kersh, who is drinking liquor. Williams positions Kersh with his chest up against the vehicle.

“So you can see, I’m not being resistant or anything,” Kersh said, while watching the video. “I’m in compliance.”

Kersh appears to cooperate for most of the video and at one point is seen talking on his cell phone with his left hand. He said he was talking to his mother, Keshia Johnson, to tell her what was happening.

Several seconds before the body slam, Williams seems to be pressing his body up against Kersh, who then turns his face toward the officer. Williams then wraps his arms around him and body slams him.

CBS 2 showed all of the videos to Dr. Geoffrey Alpert, a criminal justice expert who has testified on both sides of police misconduct cases.

“The subject is apparently being cooperative,” Alpert said. He noted Williams’ partner is seen in the video walking away to go around the car.

“So he’s not seeing any threat, not seeing any resistance,” Alpert said. “It’s just kind of a routine situation that turns very ugly, very quickly.”

Earlier this month, CBS 2 learned Williams is a trained MMA fighter. YouTube videos show him using similar maneuvers in the ring.

“That might be a good move in the ring – it’s certainly not a good move on the street,” Alpert said. “It’s not necessary to throw him to the ground. It’s clearly an excessive take down, and it’s not justified.”

Kersh and his family said he suffers from mental health issues, including schizophrenia.

Records show Kersh has been arrested more than a dozen times before his latest run-in went viral. But Johnson said that is irrelevant to how her son should have been treated by police on the day of the recent incident.

“My son does have a record, he’s done things. I can’t change what he’s done,” she said. “But he’s still a person, and what he did up until Thanksgiving has nothing to do with what this officer did to him on Thanksgiving Day. It’s not a reason, a justification, to slam his neck, his head.”

Alpert said even if Kersh did lick or spit on Williams, the officer’s reaction to take him down might be explainable, but the way he slammed him down is still not justifiable.

“This is more of a vicious lift and slam,” Alpert said. “Now, that may be OK under some circumstances, particularly on grass or some soft surface. This was on the street with a curb, and it’s not controlled. And it’s really hard to justify that vicious take down for anything.”

Alpert also said since both officers didn’t wear body cameras, there is no close-up video of the encounter and no audio to help prove their allegations that Kersh was the aggressor.

Authorities charged Kersh with one felony count of aggravated battery, one misdemeanor account of resisting police and one misdemeanor count of simple assault. He was also cited for drinking alcohol in public. He has since been released on house arrest.

After the incident, he was taken to the University of Chicago Medical Center. His attorney Andrew M. Stroth is trying to get him more thorough testing, including an independent CAT scan.

“I would have rather been tased than be slammed like that,” Kersh said. “Like I could feel my heart beat in my brain.”

The Civilian Office of Police Accountability (COPA) is investigating the incident. At COPA’s request, the police department agreed to strip Williams of his police powers, and the second officer was relieved of police duties. Police have not made Williams available for an interview.

CBS 2 uncovered Williams was also the lead officer who got a search warrant for the wrong home in February after gathering incorrect information from a confidential informant. It ultimately led to Williams and 16 other officers raiding a child’s birthday party. The family accused them of pointing guns at them and traumatizing children who were present at the time of the raid. Williams was not wearing a body camera during that incident, records show. Williams, along with the City of Chicago and four other officers, are named as co-defendants on the family’s federal civil rights lawsuit.

Nearly 10 months after that wrong raid, Williams was captured on cell phone video slamming Kersh to the ground.

Kersh said it’s still difficult for him to watch the video.

“It’s hard to look at it but…I am happy to be alive,” he said, “because I could easily not be here talking about it right now.”