The Los Angeles Police Department (LAPD) and the Drug Enforcement Administration (DEA) have launched a joint criminal investigation into the death of "Friends" star Matthew Perry, who passed away on October 28, 2023, at the age of 54. The probe comes more than six months after Perry's autopsy revealed that he died from the acute effects of ketamine, with drowning, coronary artery disease, and buprenorphine effects listed as contributing factors.

According to the autopsy report obtained by PEOPLE in December, Perry's death was ruled an accident with no signs of foul play. However, the report also noted that the levels of ketamine found in his system at the time of death could not have been solely attributed to the ketamine infusion therapy he was undergoing to treat depression, anxiety, and other health issues.

The LAPD and DEA investigation aims to determine the source of the ketamine that led to Perry's fatal overdose. An investigative source with the LAPD confirmed to PEOPLE that the department is working with the DEA and the U.S. Postal Inspector to uncover how Perry came to possess such a high amount of ketamine and how he obtained the drug in general.

While authorities have conducted several interviews, no arrests have been made thus far. The DEA declined to comment on the ongoing investigation and directed inquiries to the LAPD for updates.

The investigation into Perry's death draws parallels to other high-profile cases involving drug-related celebrity deaths. In the case of rapper Mac Miller, who died from an overdose of cocaine, alcohol, and counterfeit oxycodone containing fentanyl, two men who provided him with the fentanyl were convicted and sentenced to lengthy prison terms. Similarly, after the death of model and reality TV star Anna Nicole Smith, two doctors and her manager were charged with conspiring to provide her with prescription drugs, although the charges were eventually dismissed.

Perry, best known for his role as Chandler Bing on the hit sitcom "Friends," had been open about his struggles with addiction in the past. In his 2022 memoir, "Friends, Lovers, and the Big Terrible Thing," he shared his desire to help others facing similar challenges. "I wanted to share when I was safe from going into the dark side again," Perry told PEOPLE in a cover story. "I had to wait until I was pretty safely sober-and away from the active disease of alcoholism and addiction-to write it all down. I was pretty certain that it would help people if I did."

The entertainment industry was shaken by Perry's untimely death, with his "Friends" co-stars Lisa Kudrow, Matt LeBlanc, Courteney Cox, Jennifer Aniston, and David Schwimmer all expressing their grief and sharing touching tributes. LeBlanc, who played Perry's on-screen best friend, was the first to speak out, saying, "The times we had together are honestly among the favorite times of my life."