Thiago Silva knowingly attempted to alter the results of a urinalysis administered by the Nevada State Athletic Commission, the UFC light heavyweight admitted in a statement issued Wednesday.
In a complaint filed against the 28-year-old Brazilian mixed martial artist, the NSAC alleged that Silva's urine specimen, taken before a Jan. 1 UFC bout versus Brandon Vera in Las Vegas, reflected a "complete-invalid result" indicating it was "inconsistent with human urine." Silva is alleged to have substituted synthetic urine for his own, according to NSAC executive director Keith Kizer.
"I used a urine adulterant when giving a sample following my fight with Brandon Vera," Silva is quoted as saying in a release issued by his manager, Dan Lambert. NSAC paperwork actually shows the test was administered before the bout, Kizer said.
"I did so in an attempt to alter the results of the test and knowingly broke the rules of the Nevada Athletic Commission. This was a terrible decision on my part for which I will be punished. I am prepared to accept this punishment, learn from it and move on. I apologize to the Commission, the UFC, Brandon Vera and the MMA fans."
This is the first time Silva tested positive for a banned substance. He has tested clean on five other occasions, including one that required blood work in New Jersey. Forty-five days before his fight against Vera, Silva claimed he re-injured his back, an ailment that had kept him out of action for a year following a loss to Rashad Evans on Jan. 2, 2010.
"I made the decision to not pull out of the fight," Silva said. "I also decided that the only way I could continue with the fight was to take injections in my back and spine that contained substances prohibited by the Nevada Athletic Commission. I also made the decision to use a product to hide the presence of these substances in a urine test."
Silva did not indicate the type of illegal substances he took, how they were obtained, or who administered them.
"These decisions were mine and mine alone," he said. "I did not share this information with anyone prior to the fight for fear that I would not be allowed to fight."
Silva (15-2) showed no sign of injury en route to a unanimous decision victory against Vera, who departed the cage with a badly broken nose that required surgery.
Vera, through his manager Matt Stansell, declined to comment on the news or Silva's apology.
Kizer said it's his recommendation that the NSAC overturns Silva's win to a no-contest. The issue will be addressed at an April 7 hearing in Las Vegas. In 2006, mixed martial artist Kevin Randleman was stripped of his license to fight in Nevada for one year after similarly submitting an adulterated urine sample.
"When you make a bad decision, you can either make the situation worse by trying to cover it up or lie about it or just stick your head in the sand and refuse to acknowledge it even happened or you can own up to it with an honest explanation, accept the consequences of your actions, apologize to the people affected by it, learn from it and move on," Silva said. "I'm choosing the second option."
Josh Gross covers mixed martial arts for ESPN.com.