Stephan Bonnar's Cause of Death Released After UFC Fighter's Death

The cause of death for UFC Hall of Famer Stephan Bonnar has been revealed. According to the Clark County (Nevada) coroner's office, Bonnar's death has been ruled accidental from "Fentanyl, Parafluorofentanyl and Mitragynine intoxication," per MMA Fighting. Bonnar died on Dec. 22 in Las Vegas at the age of 45. 

Further details on Bonnar's death have not been revealed. According to the U.S. Centers for Disease Control and Prevention, fentanyl is a synthetic opioid so powerful that is up to 50 times stronger than heroin and 100 times stronger than morphine. It is found in counterfeit pills and mixed with other drugs such as heroin, cocaine and methamphetamine. It is considered by U.S. Drug Enforcement Agency administrator Anne Milgram as "the deadliest drug threat our country has ever faced."

Bonnar competed in his first UFC match in 2005 losing to Forrest Griffin in The Ultimate Fighter 1 finale. Despite the loss, Bonnar was praised for the fight which won named Fight of the Year by UFC. From there, Bonnar would become a top star in UFC and finished with a mixed martial arts record of 15-9. In 2013, Bonnar was inducted into the Fight Wing of the UFC Hall of Fame with Griffin. 

"Everything changed," Bonnar said when asked about the fight with Griffin. "I didn't think I'd have a UFC career. It was just a little hobby I was doing, so it changed everything. Almost overnight, I became like a celebrity. Everywhere I went, someone would recognize me, even in obscure places. I was traveling with TapouT and we were in a small town. I was jogging and someone in a pickup was going 'Hey Bonnar.' And everywhere you go, someone knows who you are. It was wild."  

In a 2012 interview, Bonnar talked about how the fight with Griffin made history. "That's like the best loss ever. No one really remembers the actual result, but everyone remembers the fight — that's all everyone talks about," he said. "That's just such an important moment in history for MMA — we helped put it on the map, gyms started sprouting up everywhere, little kids started to train, the list goes on." Bonnar and Griffin battled again in 2006, and Griffin won again via unanimous decision.