The federal investigation into actor Matthew Perry's death may lead to charges against multiple individuals, as reported by NBC News. Perry, best known for his role on "Friends," died from the acute effects of ketamine, drowning, and other contributing factors. Despite his reported clean period of 19 months, high levels of ketamine were found in his system at the time of his death. The federal probe, in collaboration with the Los Angeles Police Department and the Drug Enforcement Administration, is ongoing. Perry had been receiving ketamine infusion therapy for depression and anxiety, with his last treatment just before his passing. The mystery surrounding the persistence of ketamine in his system, usually metabolizing quickly, raises questions. Los Angeles police are also investigating Perry's death.