One of two doctors charged in the investigation of the death of Matthew Perry pleaded guilty on Wednesday in a federal court in Los Angeles to conspiring to distribute the surgical anesthetic ketamine. Dr Mark Chavez, 54, of San Diego, signed a plea agreement with prosecutors in August and is now the third person to plead guilty in the aftermath of the Friends star’s fatal overdose last year. Prosecutors offered lesser charges to Chavez and two others in exchange for their cooperation as they go after two targets they deem more responsible for the overdose death: another doctor and an alleged dealer who they say was known as “ketamine queen” of Los Angeles. Chavez is free on bond after turning over his passport and surrendering his medical license, among other conditions. His lawyer, Matthew Binninger, said after Chavez’s first court appearance on 30 August that he was “incredibly remorseful” and is “trying to do everything in his power to right the wrong that happened here”. Also working with federal prosecutors are Perry’s assistant, who admitted to helping him obtain and inject ketamine, and a Perry acquaintance, who admitted to acting as a drug messenger and middleman. The three are helping prosecutors in their prosecution of Dr Salvador Plasencia, charged with illegally selling ketamine to Perry in the month before his death, and Jasveen Sangha, a woman who authorities say sold the actor the lethal dose of ketamine. Both have pleaded not guilty and are awaiting trial. Chavez admitted in his plea agreement that he obtained ketamine from his former clinic and from a wholesale distributor where he submitted a fraudulent prescription. After a guilty plea, he could get up to 10 years in prison when he is sentenced. Perry was found dead by his assistant on 28 October. The medical examiner ruled ketamine was the primary cause of death. The actor had been using the drug through his regular doctor in a legal but off-label treatment for depression that has become increasingly common. Perry began seeking more ketamine than his doctor would give him, authorities say. About a month before the actor’s death, he found Plasencia, who in turn asked Chavez to obtain the drug for him. “I wonder how much this moron will pay,” Plasencia texted Chavez. The two met up the same day in Costa Mesa, halfway between Los Angeles and San Diego, and exchanged at least four vials of ketamine. After selling the drugs to Perry for $4,500, Plasencia asked Chavez if he could keep supplying them so they could become Perry’s “go-to”. Perry struggled with addiction for years, dating back to his time on Friends, when he became one of the biggest stars of his generation as Chandler Bing. He starred alongside Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer for 10 seasons from 1994 to 2004 on the mega-hit sitcom on NBC.