Matthew Perry, known for his role on 'Friends,' tragically passed away in October at the age of 54 from an accidental overdose of ketamine.

The Los Angeles police, DEA, and U.S. Postal Inspection Service are investigating how Perry obtained the drug and why he had such high levels in his system.

Perry's last ketamine infusion therapy session does not explain the toxic levels found in his blood, which were consistent with anesthesia levels used in surgical procedures.

The Los Angeles Police Department is collaborating with federal agencies to uncover the source of the ketamine.

Perry had been prescribed ketamine for depression, but the levels found in his blood were higher than expected despite his therapy.

Perry also drowned in his pool, but this was deemed a secondary factor in his death.

The investigation is ongoing, involving multiple law enforcement agencies to understand the circumstances surrounding Perry's passing.

Perry had been sober for nineteen months before his unexpected death and had expressed a desire to be remembered for helping others with sobriety.

Tributes have been paid by Hollywood figures and Canadian Prime Minister Justin Trudeau to Perry, who was a prominent figure in television.