Authorities say Hayden Panettiere may have taken fentanyl-laced oxycodone before death

Law enforcement sources told investigators that Hayden Panettiere took a single oxycodone tablet that was laced with fentanyl on the morning of her death on Aug. 16. The Drug Enforcement Administration is attempting to trace the pill to a Los Angeles supplier who had previously provided the actress with prescription drugs obtained on the black market.

Investigators said the case is complex and that further action will depend on the forthcoming toxicology report. > "The investigation is still ongoing. Law enforcement has not disclosed who they are targeting, but I am told the case is complex. We hope to have more answers soon," a representative for Panettiere said in a statement.

The Centers for Disease Control and Prevention notes that fentanyl is a synthetic opioid up to 50 times stronger than heroin and a major factor in U.S. overdose deaths.

Police reports indicate that Panettiere was found unresponsive in a Greenville, South Carolina Airbnb, and emergency responders performed CPR for an apparent overdose. A bag of medication and a dose of Narcan, an opioid antagonist, were recovered at the scene.

Brian Hickerson, the boyfriend of the actress, declined comment beyond his attorney’s statement that police found no signs of foul play and that the investigation remains ongoing. Hickerson was later detained for disorderly conduct after an altercation at a local bar, but was released without charge.