A San Diego doctor who has agreed to plead guilty as part of the investigation of the overdose death of Matthew Perry has made his first court appearance. Dr. Mark Chavez appeared Friday in federal court in Los Angeles, where he told a judge he understood his rights. The judge ordered he could remain free on bond but could not work as a doctor, among several other restrictions. Chavez has agreed with prosecutors to plead guilty to one count of conspiracy to distribute ketamine. He'll enter the plea at a later date. The “Friends” star died last year of an overdose of the powerful surgical anesthetic.