(CNN) -- "Glee" star Cory Monteith died as a result of "a mixed drug toxicity, involving heroin and alcohol," the British Columbia Coroners Service said Tuesday.
"At this point there is no evidence to suggest Mr. Monteith's death was anything other than a most-tragic accident," the coroners service said in a statement, adding that no further details were available pending a full investigation.
Monteith, 31, was found dead Saturday in his room by staff members at Vancouver's Fairmont Pacific Rim Hotel after he missed his checkout time.
The actor spent time in rehab this year, checking into a drug addiction treatment facility in late March.
Monteith had been frank about his struggles with substance abuse, telling Parade magazine in 2011 that he began using drugs at 13 and by 19 went into rehab after his mother and friends intervened.
Monteith had been on Fox's hit musical comedy show since it began in 2009, playing the dim quarterback of the football team who is forced to join the glee club. After graduation, he comes back to town and helps direct a musical at the school.
Adam Shankman, who directed an episode for each of the past three seasons, told CNN's Poppy Harlow that he had talked to Monteith on Saturday morning. The actor said he wanted to come down to California to Jet Ski.
Shankman described Monteith as the glue of "Glee." He was always welcoming, whether it was to a guest director or a new cast member, Shankman said.
The actor knew all of his lines when filming began each time and would congratulate his fellow cast members when he thought they did well.
"He showed up every day, and he was a delight," Shankman said.
Offscreen, Monteith was dating co-star and on-screen love interest Lea Michele.
He was madly in love with her, Shankman said. "He felt like it had renewed his spirit."
Representatives for Michele issued a brief statement Monday saying the actress is "deeply grateful for all the love and support she has received from family, friends, and fans."
"Since Cory's passing, Lea has been grieving alongside his family and making appropriate arrangements with them," the statement said. "They are supporting each other as they endure this profound loss together."
CNN's Steve Almasy and Amanda Watts contributed to this report.