One of two doctors charged in connection with Matthew Perry’s death will appear in court in Los Angeles on Friday, where he is expected to plead guilty to conspiring to distribute the surgical anaesthetic ketamine. Dr Mark Chavez, 54, reached a plea agreement with prosecutors earlier this month and would be the third person to plead guilty in the aftermath of the Friends’ star’s fatal overdose last year. Chavez agreed to co-operate with prosecutors as they pursue others, including the doctor Chavez worked with to sell ketamine to Perry.

Also working with the US attorney’s office are Perry’s assistant, who admitted helping him obtain and inject ketamine, and a Perry acquaintance, who admitted acting as a drug messenger and middleman. The three are helping prosecutors as they go after their main targets, Dr Salvador Plasencia, charged with illegally selling ketamine to Perry in the month before his death, and Jasveen Sangha, a woman who authorities say is a dealer who sold the actor the lethal dose of ketamine. Matthew Perry at the 64th Primetime Emmy Awards in Los Angeles in 2012 (Jordan Strauss/Invision/AP) 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 October 28. The medical examiner ruled ketamine was the primary cause of deat.