Cory Monteith, star of the hit TV musical comedy Glee, died from a heroin and alcohol overdose, a coroner in British Columbia has announced.
The 31-year-old Canadian, who played Finn Hudson on the show, was found dead in a Vancouver hotel room on Saturday.
The coroner said there was no evidence to suggest his death was "anything other than a most tragic accident".
Monteith, who had been in the musical comedy since its 2009 start, was treated for drug addiction in April.
The actor is thought to have been alone when he died as hotel video and electronic records showed he returned to his room by himself early on Saturday, after spending time with other people.
The alarm was raised when he failed to check out at midday on 13 July. He had been staying at the hotel for a week.
Police said they believed Monteith had been dead for several hours before he was found.
Monteith's girlfriend Lea Michele, who starred alongside him in Glee, issued a statement saying she was "deeply grateful for all the love and support she's received from family, friends, and fans".
The statement, given to People magazine, said she had been "grieving alongside his family and making appropriate arrangements with them" and "they are supporting each other as they endure this profound loss together".
"We continue to ask the media to respect the privacy of Lea and Cory's family," it concluded.
Monteith had previously talked frankly about struggling with addiction since he was a teenager.
He was treated for drug abuse aged 19 and later told one interviewer he took "anything and everything" and now felt "lucky to be alive".
He took time out from Glee to go into rehab in April, which meant he missed filming the final episodes of the fourth series.
At the time 20th Century Fox Television, which makes Glee, issued a statement of support saying the show looked forward to his return.
The show follows a group of American high school misfits who form a glee club in their quest for singing contest glory.
Monteith played the school's star quarterback who risked alienation by his friends after joining the club.
Known for its melodic covers and celebrity cameo appearances, Glee's four series made global celebrities of its cast.
The show has won a number of Emmy and Golden Globe awards and featured guest spots by Britney Spears, Gwyneth Paltrow and Neil Patrick Harris.