Star boxer Ryan Garcia's B-sample returned an adverse finding for the banned substance ostarine on Thursday, per a Sports Medicine Research and Testing Laboratory report viewed by ESPN.

The A-sample, which was collected the day before and the day of his upset win over Devin Haney last month, returned an adverse finding for ostarine May 1.

Ostarine is a selective androgen receptor modulator (SARM) that attaches to proteins in the body and effectively signals for muscles to grow. It is used to aid performance by helping athletes build muscle mass and enhance their rate of fat loss, as well as to increase stamina and recovery ability.

Ostarine has been on the World Anti-Doping Agency's banned list since 2008 and in 2022 was listed as an anabolic agent by WADA, whose rules mandate that when urine samples are collected, they are divided into A and B bottles to safeguard against lab error.

"I don't know where [the adverse finding] came from," Garcia told ESPN on Saturday in Riyadh, Saudi Arabia, hours before he was ringside for Oleksandr Usyk's heavyweight title win over Tyson Fury. "Honestly, bro, I don't. I was taking ashwagandha, D-3, Omega-3, just normal s---. I don't know what the f--- [ostarine] is. ... I have seriously no idea. I would tell everybody the truth.

"My whole thing is I'd rather tell the truth than try to fabricate it with a lie. Because lies don't stand. So if I really did take it, I would be like, honestly, I was going through a weird situation. I wasn't really that confident. I chose to take it. I'm sorry. And that's it. But I didn't and I hate cheating. ... All I can say is legal team, help me figure this out."

Darin Chavez, part of Garcia's four-member legal team, told ESPN a formal hearing with the New York State Athletic Commission will be set to "absolve Garcia of any wrongdoing."

" ... Soon after being notified of his positive test, Ryan voluntarily had his hair collected and shipped to Dr. Pascal Kintz, the foremost expert in toxicology and hair-sample analysis," Chavez said. "The results of Ryan's hair sample came back negative. ... We are certain that one of the natural supplements Ryan was using in the lead up to the fight will prove to be contaminated. We are in the process of testing the supplements to determine the exact source."

The commission issued a statement Thursday saying the matter is still under review.

"The Commission strictly prohibits the use of performance enhancing drugs and works vigorously to uphold the integrity of the sport and maintain a level playing field," the statement said. "Where violations are found, the Commission will take action."

If Garcia (25-1, 20 KOs) and his team can indeed prove to the commission that there was supplement contamination, then the 25-year-old could be cleared. Otherwise, he faces suspension of his boxing license along with fines.

Garcia, who floored Haney three times in the majority-decision win, lashed out at Victor Conte, who works with Haney as a sports nutritionist and performance adviser.

"This dude that's f---ing defending Devin Haney is the biggest cheater in sports history," Garcia said. "You can't make this up." Conte, the founder of Bay Area Laboratory Co-Operative (BALCO), served time in prison after pleading guilty to conspiracy to distribute performance-enhancing drugs before founding SNAC, a sports nutrition company.

"Ryan Garcia has called me lots of horrible names recently," Conte told ESPN. "However, the scientific process was upheld and both of his urine B-samples came back positive for ostarine. The strict liability rule will now apply and he will likely be fined and suspended from boxing. I hope Ryan's behavior will serve as an example of how not to act in times of uncertainty in regards to pending drug testing results. ... The world of boxing deserves to be respected as a sport."

Ostarine has been used in boxing before. Lucian Bute tested positive for it in 2016 following a draw with Badou Jack in their WBC super middleweight title fight. The result was changed to a DQ win for Jack. Amir Khan was handed a two-year ban by UK Anti-Doping (UKAD) after he tested positive for ostarine following his sixth-round TKO loss to Kell Brook in 2022.

"It's been tough," Garcia said. "I know I've been talking my s---, but alone it's been hurting me a little bit and I've been sad and I feel like crying. I even feel like crying right now because it's just like they're taking my greatest victory away. But again, leave it in God's hands. ... At the end of the day, I just feel like I try to fight for my innocence every day, man. I've been giving them the facts about what they're doing and how it ended up being a positive the day before and the day after."

"I know I will find a way to fight," Garcia added regarding a possible suspension. "If I got to go to a different country to fight, I will. ... I just want to be in the ring. I'm in my prime. I feel good. I feel strong."