A man battling colon cancer says he was body slammed by a Nassau police officer while attempting to see his dying mother at Nassau University Medical Center.

Gary Leifer, 59, told News 12 Long Island that he was following an ambulance that was carrying his 84-year-old mother. When it arrived at NUMC, he parked his car and raced toward the entrance to be at her side, but was stopped by a Nassau officer.

"I run all the way up there, I see them giving her compressions. He says, 'Go move your car,'" says Leifer. "I say, 'That's my mother right there. Let me just see her.'"

Leifer says the officer body slammed him after he tried to get around him. He was left with bruises and scratches to his back.

He says he's filed a complaint with the Nassau Police Department and the Nassau District Attorney's Office.

"I don't care about the pain. I don't care about the beating. This guy's going to kill somebody," says Leifer.

Nassau police have confirmed that Leifer has filed a complaint with the department's internal affairs bureau. They say they cannot comment due to an open investigation. The district attorney's office says allegations of police misconduct are investigated by internal affairs.