Koppenhaver, 32, faces charges of attempted murder, domestic battery by strangulation, first-degree kidnapping and sexual assault, stemming from an alleged incident involving his ex-girlfriend and adult film actress Christy Mack on Aug. 8 at Mack's Las Vegas residence. The professional mixed martial artist faces the possibility of life in prison.
A preliminary hearing has been scheduled on Oct. 17. Koppenhaver was extradited to Las Vegas from Ventura County, California, on Aug. 30 after he was arrested in a Los Angeles suburb.
After the alleged attack, Mack released a statement detailing the incident via social media. According to the statement, Koppenhaver attacked Mack and a male friend at her residence in the early morning hours of Aug. 8 and threatened her life with a knife. Mack said she escaped out a back door and sought help in her neighborhood. She was eventually hospitalized in Las Vegas.
Koppenhaver is a former contestant on the UFC's reality series "The Ultimate Fighter." He signed with Bellator MMA in 2013. The promotion released the welterweight shortly after reports surfaced of the alleged incident.
Koppenhaver legally changed his name to War Machine in 2008, but is listed by his birth name in the Las Vegas court system. In 2012, he was convicted and served time for an attempt to commit battery with substantial bodily harm in Las Vegas.