Thiago Silva's urine sample in question

Updated: March 29, 2011, 6:14 PM ET
By Josh Gross | ESPN.com

UFC light heavyweight Thiago Silva "submitted an adulterated and/or substituted urine specimen" as part of a drug screening in Nevada leading up to his fight with Brandon Vera on Jan. 1, a complaint filed by the Nevada State Athletic Commission against the fighter alleges.

The urinalysis reflects a "complete-invalid result indicating that the specimen by Silva is inconsistent with human urine," according to the complaint's factual allegations, which were released Tuesday by the commission.

Silva's manager Dan Lambert declined to provide an immediate comment when reached by ESPN.com. He said Silva (15-2) would provide a statement.

Silva's sample was tested twice. The confirming B Sample was tested by the Sports Medicine Research & Testing Laboratory, a facility accredited by the World Anti-Doping Agency. NSAC executive director Keith Kizer said Silva's sample was consistent with synthetic urine, but did not show any masking agents.

Silva, a 28-year-old fighter from Sao Paulo, Brazil, defeated Vera on points at UFC 125. Silva, who battered Vera throughout the three-round fight, has 20 days from receipt of the complaint to file an answer with the NSAC, Kizer said.

A hearing on Silva's temporary suspension will be held in Las Vegas on April 7.

NSAC can also overturn victories to no contests in cases like this. Kizer said he will ask to overturn the result, which would be discussed at Silva's hearing.

Silva's sample was tested twice. The confirming B Sample was tested by the Sports Medicine Research & Testing Laboratory, a facility accredited by the World Anti-Doping Agency.

Josh Gross covers mixed martial arts for ESPN.com.