The investigation into actress Hayden Panettiere’s sudden death has taken a major turn, with law enforcement sources indicating she took one oxycodone pill suspected of containing fentanyl.

Panettiere, 36, died on August 16 after being found unresponsive at a temporary residence in Greenville, South Carolina. Investigators now believe the pill may have originated from a longtime Los Angeles drug supplier.

The Drug Enforcement Administration is working to trace the pill back to its source. Toxicology results remain pending, meaning the fentanyl-laced pill remains the leading theory but has not yet been confirmed by the coroner.

Panettiere had previously spoken publicly about her battles with alcohol and opioid addiction, postpartum depression, and recovery. Her memoir, “This Is Me: A Reckoning,” was published only months before her death.

The Greenville County Coroner’s Office noted that the autopsy found no signs of trauma contributing to her death and that the official cause and manner of death remain pending until additional studies are completed.

Authorities have also investigated Panettiere’s relationship with a suspected drug supplier in Los Angeles. Security video from the apartment complex helped build a timeline of events leading up to her death.

Panettiere’s on-again, off-again boyfriend, Brian Hickerson, was present at the apartment when she died and reportedly showed an officer a bag containing medications she had been taking. Hickerson has spoken with federal investigators but has not been charged in connection with her death.