The Greenville County Coroner's Office has revealed the cause of Hayden Panettiere's death, ruling that the actress died from an accidental overdose involving fentanyl and several other drugs.

According to the autopsy report, cited by CBS News, the cause of death was listed as the "toxic effects" of fentanyl, 4-ANPP, alprazolam, methocarbamol and quetiapine. The manner of death was ruled an accident.

What the Coroner's Report Found

Emergency responders were called to a residence in Greenville, South Carolina, on the afternoon of Aug. 16, where Panettiere had been staying, according to NBC News. The coroner's office said there were no signs of trauma, and police had previously said their preliminary investigation turned up no indication of foul play or suspicious circumstances. 4-ANPP is a chemical precursor used in the illicit manufacture of fentanyl and is sometimes found alongside it in toxicology results; alprazolam, methocarbamol and quetiapine are, respectively, an anti-anxiety medication, a muscle relaxant and a drug sometimes prescribed for insomnia or mood disorders.

THE MANNER OF DEATH WAS RULED AN ACCIDENT

Panettiere, who died five days before what would have been her 37th birthday, first became a household name as a child actress before breaking out as cheerleader Claire Bennet in NBC's "Heroes," a role that made her one of the most recognizable young stars on network television. She later starred as country singer Juliette Barnes in ABC's "Nashville," a part that showcased both her acting and singing and won her a devoted fanbase well beyond the show's run.

The actress had spoken openly in past years about struggles with substance abuse, postpartum depression and mental health, using her platform at various points to advocate for more open conversations about addiction and recovery. Tributes from former co-stars and fans followed news of her death, with many recalling her warmth on set and her willingness to discuss her struggles publicly rather than hide them.

Outlets including Variety and Newsweek noted that fentanyl-linked deaths have continued to climb across the entertainment industry and the country more broadly, even as public health officials have ramped up warnings about the drug's presence — often undetected — in counterfeit pills and other substances.