One of two doctors charged in the investigation of the death of Matthew Perry is expected to plead 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 would be 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 that they say was known as 'ketamine queen' of Los Angeles.