The "Glee" star was found dead in a Vancouver hotel room July 13, 20013. He was 31.
Billboard.com quoted the B.C. coroner's report as saying Monteith died of a mixed drug cocktail involving "intravenous heroin use combined with the ingestion of alcohol."
The report also noted investigators on the scene discovered "a spoon with drug residue and a used hypodermic needle, along with two empty champagne bottles and glasses" when they entered Monteith's room after he did not check out of the hotel as scheduled.