Dog the Bounty Hunter joins manhunt for cage fighter who brutally beat porn actress

(Reuters) - Reality television star Duane Chapman, better known as Dog the Bounty Hunter, said Wednesday he was joining the manhunt for a professional mixed martial artist whose ex-girlfriend has accused him of a brutal attack on her and a friend.

Jonathan Koppenhaver, also known by the name "War Machine" for his time in the Ultimate Fighting Championship, is wanted by the Las Vegas Metropolitan Police Department for questioning in connection with the Aug. 8 attack.

Police have not released the names of the two victims but Koppenhaver's former girlfriend, porn actress Christy Mack, said on Twitter that she he suffered 18 broken facial bones, a broken nose and rib and had her liver ruptured.

Dog the Bounty Hunter, whose show about chasing fugitives is carried on the A&E channel, said in a series of tweets that he and his bounty-hunting team were going to help Las Vegas authorities hunt down Koppenhaver.

"Time is up! BEWARE OF THE DOG," one tweet read.

Mack, who posted photos of her injuries on social media, said Koppenhaver entered her Las Vegas home about 4 a.m. while she was with a friend, and immediately attacked the pair.

She said that Koppenhaver had beaten her "many times before, but never this badly."

He faces felony charges of domestic battery with substantial bodily harm, assault with a deadly weapon and battery by strangulation, police said.

Koppenhaver also responded to the allegations by social media. "The cops will never give me fair play, never believe me. Still deciding what to do but at the end of the day it's all just heart breaking," he posted on Twitter.

Bellator MMA, a mixed martial arts promotion company that sponsored Koppenhaver, cut ties with him after news of the assault surfaced.

(Reporting by Victoria Cavaliere in Seattle; Editing by Daniel Wallis and Bill Trott)