LAS VEGAS -- Fugitive mixed martial arts fighter War Machine was arrested Friday in California on suspicion of beating his ex-girlfriend so severely in Las Vegas that she feared for her life.

The 32-year-old fighter and former porn actor, whose birth name is Jon Koppenhaver, was captured in the Los Angeles suburb of Simi Valley.

Authorities issued a warrant for Koppenhaver on Monday, the same day his ex-girlfriend, adult film actress Christy Mack, posted graphic photos of her swollen, beaten face online.

Mack said in a statement that Koppenhaver showed up unannounced at her house on Aug. 8, found her and a friend unarmed, and beat the friend without uttering a word.

Koppenhaver then sent the friend away and turned to Mack, forcing her to shower before knocking out some of her teeth and breaking bones in her face, the statement said.

She wrote that she feared for her life as he sawed off her hair with a dull knife.

Mack said she was able to escape out a back door and run naked through her neighbourhood, knocking on doors until someone helped her get to a hospital.

Koppenhaver had been abusive in the past and broke up with her in May, she said.

"After many months of fear and pressure to keep this man happy, I feel that I can no longer put myself in this situation," Mack wrote.

Koppenhaver did not return a message Tuesday seeking comment about Mack's account, and it's not clear whether he has an attorney.

The welterweight fighter made his Ultimate Fighting Championship debut in 2007. He lost his only pay-per-view bout in 2008 and went on to fight for a variety of promotions over the past five years.

His criminal record includes a 2012 conviction for attempt to commit battery with substantial bodily harm.

U.S. marshals said they worked with police and Department of Homeland Security agents to capture Koppenhaver. He was booked into the Simi Valley Jail while awaiting extradition to Nevada.

"This is yet another example of how our joint agency efforts are apprehending fugitives who think they can hide," District of Nevada U.S. Marshal Christopher Hoye said in a statement.