By Sarah Michaud and Karen Mizoguchi
November 05, 2018 at 12:00 PM EST
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Mac Miller‘s cause of death has been revealed.

The 26-year-old rapper — who was found dead in his Studio City, California, home on Sept. 7 — died of an accidental overdose of fentanyl, cocaine and alcohol, PEOPLE confirmed. The Los Angeles County Department of Medical Examiner-Coroner ruled in a statement released Monday that Miller’s death was accidental and due to mixed drug toxicity.

The autopsy was completed three days after the star’s death and his body was released to his family, according to Los Angeles County coroner’s spokeswoman Sarah Ardalani.

Robin Marchant/Getty Images

RELATED: Chance the Rapper, John Mayer, more celebrate Mac Miller at emotional tribute concert

A source previously told PEOPLE Miller, born Malcolm James McCormick, had gone into cardiac arrest after appearing to suffer a drug overdose. At the time, PEOPLE confirmed that paramedics never transported him to a hospital, and he had already died before he was found unresponsive and could not be revived.

Miller’s home was reportedly “swept clean” so that there would be no evidence of drug use, according to TMZ, which also reported that only a small amount of white powder was found in Miller’s home when police searched for clues as to how he died.

At the time, an insider told PEOPLE that Miller, who just dropped his fifth and final studio album Swimming on Aug. 3, spent the evening before his death watching football with friends.

Miller’s casual night with friends seemed so benign, “that’s why this is such a shock,” the insider said. “Everyone who he worked with was aware that he was delicate, but thought it was because of the new album, nerves, nothing like this.”

During his lifetime, the rapper was open about his battle with substance abuse.

In a 2016 short documentary by music magazine The Fader, Miller explained how he came to rely so heavily on codeine-based cough syrup mixed with soda.

“It started by me just sitting inside all day and then it’s like, then you get bored. Then you’re like, ‘Well I could just be high, and I could have a whole adventure in this room,’ ” the “Self Care” rapper began. “I’m always like, if someone’s like, ‘You wanna try this?’ I’m like, ‘Yeah sure.’ It f—s you up when you have a bunch of money because you try a drug, you like it, then you can buy a lot of it. I went through about everything.”

RELATED: Mac Miller’s Will Reveals He Left His Entire Estate to His Parents

Miller was arrested for DUI in May, less than a week after his split from ex Ariana Grande was made public, but the Los Angeles city attorney confirmed the charges would be dropped in the case.

Christopher Polk for EW

Last week, Mac Miller‘s legacy and music career were honored at his celebration of life concert benefitting the newly formed The Mac Miller Circles Fund.

The star was remembered by many of his famous friends and former collaborators including Action Bronson, Anderson.Paak, Chance the Rapper, Dylan Reynolds, Domo Genesis, Earl Sweatshirt, J.I.D, John Mayer, Miguel, Njomza, ScHoolboy Q, SZA, Thundercat, Travis Scott, Ty Dolla $ign and Vince Staples.