Golden Boy Promotions said in a statement Thursday that it stands by Ryan Garcia after a report that he had tested positive for a banned substance before his dominant victory over Devin Haney last month in New York.

“Ryan has put out multiple statements denying knowingly using any banned substances — and we believe him,” the statement read. “We are working with his team to determine how this finding came to be and will address this further once we conclude that process.”

ESPN reported that Garcia tested positive for the performance-enhancing substance Ostarine the day before and the day of the April 20 fight, citing a Voluntary Anti-Doping Association letter. Ostarine is a selective androgen receptor modulator, and its use can stimulate muscle growth. It is banned by the World Anti-Doping Agency. The results of the test weren’t known until later.