Five people have been charged in the drug-related death of actor Matthew Perry.

The 54-year-old passed away at his Los Angeles home in October last year.

A post-mortem found a high concentration of

ketamine in his blood and determined that the “acute effects” of the controlled substance had killed him.

BBC News says those charged included two doctors and the actor’s personal assistant, with police reportedly uncovering a “broad underground criminal network” of drug suppliers who distributed large quantities of ketamine.

US Attorney Martin Estrada said “These defendants took advantage of Mr Perry’s addiction issues to enrich themselves. They knew what they were doing was risking great danger to Mr Perry, but they did it anyway.”

Ketamine – a powerful anaesthetic – is used as a treatment for depression, anxiety and pain.