NEWPORT BEACH, Calif. — Mike "Mad Dog" Bell, a former professional wrestler whose struggle with substance abuse was featured in the documentary "Bigger, Stronger, Faster," has died. He was 37.

Bell was found Sunday at a Costa Mesa live-in rehabilitation facility, his family said.

An autopsy was conducted but investigators couldn't immediately determine the cause of death, said Dan Akin, a supervising deputy at the Orange County coroner's division. The coroner is awaiting the results of toxicology tests, he said.

Chris Bell, whose 2008 documentary examines the steroid use of his two brothers, said Mike Bell had long battled with his addictions to prescription painkillers and alcohol.

"He was always wrestling, he was a personal trainer, he was always pushing his body to the max," Chris Bell told the Orange County Register.

"You can't really blame wrestling, but it's kind of the lifestyle," he said. "You have a couple of painkillers to get to the next match, have a couple drinks night to night and it gets out of hand."

Bell wrestled on World Wrestling Entertainment's "Monday Night Raw" as a "jobber," a fighter who takes falls to promote others.

"Although Mr. Bell was never under a WWE contract, WWE extends its deepest condolences to the Bell family," the organization said.