Officials Reveal Cause of Death for UFC Hall of Famer Stephan Bonnar

Mixed martial arts fighter Stephan Bonnar of the United States poses during the Ultimate Fighting Championship (UFC) 153 weigh-in event in Rio de Janeiro on Oct. 12, 2012. Felipe Dana/AP Photo

Officials have given a cause of death for former fighter and UFC Hall of Famer Stephan Bonnar, who passed away in December at the age of 45.

The Clark County’s office in Nevada confirmed in an emailed statement to MMA Fighting that Bonnar’s death was due to accidental “Fentanyl, Parafluorofentanyl, and Mitragynine intoxication.”