Six months after Matthew Perry’s tragic death sent ripples around the world, the Los Angeles Police Department and the Drug Enforcement Administration have launched a joint criminal investigation into how he died, the LAPD told The Hollywood Reporter. ...

But now, the LAPD and DEA are investigating how the actor came to have so much of the drug in his system and possession in general.

Perry had been undergoing ketamine infusion therapy, which is said to help with depression, anxiety, PTSD, drug and alcohol problems, chronic pain and more. His last session had been a week and a half before he died. According to the autopsy, “the ketamine in his system at death could not be from that infusion therapy since ketamine’s half-life is three to four hours or less.”