Police have launched a criminal investigation into the death of "Friends" star Matthew Perry, who died at 54 in October last year. Perry was found unresponsive in his Los Angeles home. The LA County Medical Examiner’s Office determined he died from "acute effects of ketamine" with drowning, coronary artery disease, and opioid buprenorphine as contributing factors. Despite Perry undergoing ketamine infusion therapy for anxiety and depression, his last known infusion was over a week before his death, suggesting the drugs in his system weren't from medical treatment. The LAPD, in collaboration with the DEA and the US Postal Inspection Service, is investigating how Perry obtained the drugs. The robbery-homicide division leads the inquiry, with no arrests made yet. Perry's struggle with addiction was well-documented in his memoir, and his "Friends" co-star Courteney Cox mentioned feeling his presence frequently since his passing.