Philip Seymour Hoffman died from an overdose of both uppers and downers, including heroin, cocaine, amphetamines and benzodiazepines, the New York medical examiner concluded Friday.
The death was ruled accidental, and the official cause was listed as acute mixed drug intoxication.
Hoffman, 46, one of the most acclaimed actors of his generation, was found dead in his New York apartment Feb. 2 with a syringe in his arm.
He had struggled with addiction. Private diaries found in the apartment contain entries about personal demons, drug deals and attempts to stay clean by attending Narcotics Anonymous meetings, according to people familiar with the contents.
Hoffman, who won an Oscar for "Capote" and starred in numerous other movies as well as New York stage productions, had been open about struggling with substance abuse.
He told CBS' "60 Minutes" in 2006 that had he used "anything I could get my hands on" before getting clean at age 22. But in interviews last year, he said he'd relapsed, had developed a heroin problem and had gone to rehab for a time.
A musician, veteran jazz player Robert Vineberg, has been charged with keeping a heroin stash in a lower Manhattan apartment amid the investigation into Hoffman's death.
Vineberg, who has said he was a friend of the Tony Award-nominated Hoffman, hasn't been charged in Hoffman's death and has said he didn't sell him the heroin found in his apartment.