Joel Casamayor tested positive for marijuana following his knockout loss to junior welterweight titlist Timothy Bradley Jr. on Saturday's Manny Pacquiao-Juan Manuel Marquez III undercard in Las Vegas, according to the Nevada State Athletic Commission.
Commission executive director Keith Kizer told ESPN.com that the commission would file a complaint against Casamayor, a former lightweight and junior lightweight champion. After Casamayor responds to the complaint, Kizer said a hearing would be scheduled.
"It's unfortunate. If the commission finds him in violation of the drug-testing regulations, they could fine him or suspend him, or a combination thereof," Kizer said Thursday.
Like the other fighters on the card, Casamayor provided a urine sample following the fight; the sample was tested for drugs and stimulants. The commission also runs steroid tests on samples, but those results have yet to come back.
The commission could fine Casamayor up to 100 percent of his $100,000 purse, although that is unlikely. Casamayor had $6,600 withheld from his purse for a child-support claim, which Kizer said the commission would not interfere with.
The 40-year-old Casamayor (38-6-1, 22 KOs), a 1996 Cuban Olympic gold medalist who is long past his prime, had problems making weight. He was one pound over the 140-pound limit and needed a second try nearly two hours later to make weight the day before the fight.
Casamayor showed very little as Bradley (28-0, 12 KOs) steamrolled him. Bradley knocked him down in the fifth, sixth and eighth rounds before cornerman Miguel Diaz threw in the towel and referee Vic Drakulich stopped the fight.
Dan Rafael is the senior boxing writer for ESPN.com. Follow him on Twitter @danrafaelespn.