Almost a month after the sudden death of Hollywood star Hayden Panettiere at just 36, investigators believe they now know what claimed her life.
The Heroes and Nashville actress is believed to have died after taking a single oxycodone pill that had been laced with the powerful synthetic opioid fentanyl.
Multiple law enforcement sources with knowledge of the investigation have told US media that Panettiere took the pill on the morning of August 16, while staying in Greenville, South Carolina.
The revelation comes as authorities continue investigating where the drug came from, with the US Drug Enforcement Administration reportedly involved in a cross-country probe spanning South Carolina and Los Angeles.
According to reports, investigators believe Panettiere had been obtaining black-market prescription medication, including oxycodone, from a long-time dealer in Los Angeles.
She is understood to have travelled from Los Angeles to South Carolina the day before her death, with sources claiming she had taken several drugs supplied to her during the journey. Investigators believe it was an oxycodone pill taken the following morning, however, that contained fentanyl and proved fatal.
Authorities are now attempting to trace the pill back to its source.
Official toxicology results are still pending, meaning Panettiere’s formal cause and manner of death have not yet been released by the Greenville County Coroner’s Office. The fentanyl-laced pill remains investigators’ working theory.
Panettiere was found unresponsive and in cardiac arrest at a residence in Greenville on August 16 after emergency services were called to the property.
Paramedics attempted advanced life support but were unable to revive her, and she was pronounced dead at 2.32pm.
An autopsy conducted the following day found no signs of trauma that could have contributed to her death, while police said their initial investigation had uncovered no evidence of foul play or suspicious circumstances.
Panettiere had spoken openly over the years about her struggles with addiction, including in her 2026 memoir, This is Me: A Reckoning.
Her death stunned fans around the world. Beginning her career as a child actor, Panettiere went on to become best known for playing cheerleader Claire Bennet in Heroes and country singer Juliette Barnes in Nashville. Her film credits included Remember the Titans and the Scream franchise.
Announcing her death last month, her father, Skip Panettiere, remembered his daughter as “an incredible light and a force of nature” who had brought joy to those who knew her and millions who watched her on screen.
The investigation into the circumstances surrounding her death remains ongoing.
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