Chicago officer caught on video body-slamming man used same move as an MMA fighter

Chicago — A Chicago police officer caught on video smashing a mentally ill man's head into the pavement is now facing a probe into whether he used excessive force. A new video is raising questions about the technique he used.

In cellphone video taken by a bystander, officer Jerald Williams is seen body-slamming a man he'd been ticketing for drinking in public. It looked less like something he learned in the police academy, and more like something from a mixed martial arts cage match. Video shows him doing the same move.

In the ring, Williams is known as Jerald "Bacon and Eggs" Williams. On the Chicago streets, he's assigned to the area south gang enforcement unit.

The victim's family says he is a man with schizophrenia named Bernard Kersh who was unarmed and accused of threatening the officer and trying to lick him. He was knocked unconscious and hospitalized. His mother, Keshia Johnson, said he's still having headaches.

"My son could have been killed. I think more needs to be done," she said.

Kersh's attorney called the body slam "excessive force."

"We think, based on that martial arts take down, it was potential lethal force," attorney Andrew Stroth said.

While the body slam incident is under investigation, Williams and his partner have been taken off the street and put on desk duty. 

CBS News reached out to the police and were told Williams would not be available for an interview.