Cory Monteith's Cause of Death: Heroin and Alcohol

Cory Monteith's autopsy results are in.

The "Glee" actor died of a mixed drug toxicity involving heroin and alcohol, the British Columbia Coroners Service confirmed on Tuesday.

Monteith was found dead in his room at the Fairmont Pacific Rim hotel in downtown Vancouver, British Columbia, shortly after noon on Saturday when he failed to check out on time.

[Related: How Will 'Glee' Cope With Cory Monteith's Death and How Have Other Shows Done It?]

"It should be noted that at this point there is no evidence to suggest Mr. Monteith's death was anything other than a most-tragic accident," the coroners office said in a statement.

Yahoo! TV can also confirm the police investigation into Monteith's death has been concluded. The findings indicate that Monteith was alone when he died and there was evidence in his hotel room consistent with the autopsy and toxicology findings of an overdose. The three people the actor was out with the night before were "very cooperative," leaving the police to feel like there is nothing further to investigate.

Girlfriend and "Glee" co-star Lea Michele has issued the following statement to People magazine following the coroners report: "Lea is deeply grateful for all the love and support she’s received from family, friends, and fans. Since Cory’s passing, Lea has been grieving alongside his family and making appropriate arrangements with them. 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."

[Related: Cory Monteith's Final Film Performance: Actor Tapped Troubled Past for Gritty Role]

While Monteith was open about his struggles with substance abuse over the years, the cause of death is still a shock to those who were close to him.

Gia Milani, who recently produced and directed a Canadian film "All the Wrong Reasons" featuring Monteith, said the actor "seemed healthy" when she last saw him four weeks ago in Los Angeles, according to the AP. "He looked super fit and he was energetic and excited," she said.

Sources close to the late actor tell Yahoo! TV that even in the days leading up to his death, Monteith "seemed great."

"He honestly seemed happier and healthier than ever," one insider says, who spoke to Monteith last week. "This is devastating and shocking on so many levels."

[Related: 'Glee' Co-Stars and More React to Cory Monteith's Death]

In March, the 31-year-old actor voluntarily admitted himself into a treatment facility for substance abuse. Michele privately and publicly stood by Monteith's side while he got help.

Monteith first publicly detailed his troubles with drugs and alcohol that started at age 13 during an interview with Parade in June 2011.

"I was out of control," he admitted, adding "Anything and everything, as much as possible," was his drug of choice. “I had a serious problem.”

[Related: Cory Monteith's Ex-Girlfriend: He 'Kept Me in the Dark' About Drug Addiction]

Monteith later explained why he decided to share his story with the world: "I felt like I had to step in at some point and relate to people my experience, and relate to people the truth of my life and where I come from."

Our hearts go out to Monteith's family, friends, and girlfriend Michele during this difficult time.

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