Hayden Panettiere’s sudden death at age 36 remains under investigation, but authorities are now reportedly looking closely at a single pill she may have taken during her final hours.

According to TMZ, law enforcement sources connected to the investigation believe Panettiere took what she thought was oxycodone on the morning she died. Investigators are working under the theory that the pill may have been laced with fentanyl, a powerful synthetic opioid.

However, that has not yet been confirmed as her official cause of death. Toxicology results are still pending and could ultimately determine what substances were in her system.

Investigators Focus on Final Hours

Panettiere died on Aug. 16, 2026, after being found unresponsive in Greenville, South Carolina. She had traveled there from Los Angeles the previous day with her boyfriend, Brian Hickerson.

TMZ reports that investigators believe Panettiere had a longtime drug dealer in Los Angeles who allegedly supplied her with black-market prescription drugs, including oxycodone.

Sources told the outlet that Panettiere allegedly took several drugs obtained from the dealer while traveling from Los Angeles to South Carolina.

Authorities are now reportedly investigating whether a pill she took the following morning contained fentanyl.

The DEA in Los Angeles is said to be examining Panettiere’s alleged relationship with the dealer and trying to determine where the suspected pill came from.

The investigation reportedly involves authorities in both South Carolina and California.

Toxicology Results Could Provide Answers

Law enforcement sources stressed to TMZ that the investigation remains dependent on Panettiere’s toxicology results.

For now, the fentanyl-laced oxycodone pill is described as a working theory, rather than a confirmed cause of death.

There were signs at the scene that an overdose was considered a possibility.

When first responders arrived, Hickerson reportedly gave them a bag containing Panettiere’s prescription medications. Investigators could examine those medications as they work to determine exactly what happened.

Hickerson also reportedly administered Narcan to Panettiere after she became unresponsive. Narcan, also known as naloxone, is used to rapidly reverse the effects of an opioid overdose.

Despite those efforts, Panettiere could not be revived.

Her autopsy was completed the following day, but an official cause and manner of death were not immediately released.

A Career That Began in Childhood

Panettiere had spent most of her life in the public eye.

Born Aug. 21, 1989, in Palisades, New York, she began working as a child and appeared in commercials before moving into television and movies.

As a young actress, she appeared on soap operas including One Life to Live and Guiding Light. She also appeared in movies such as Remember the Titans and Raising Helen.

Her major breakthrough came when she was cast as cheerleader Claire Bennet on NBC’s hit series Heroes. Her character had the ability to heal from serious injuries, and Panettiere quickly became one of the show’s most recognizable stars.

She later found another major television role as country singer Juliette Barnes on Nashville. The role earned her Golden Globe nominations and allowed her to showcase both her acting and singing abilities.

Panettiere also appeared in movies including I Love You, Beth Cooper and Scream 4. Years later, she returned to the Scream franchise as fan-favorite character Kirby Reed.

She Had Spoken About Addiction

Away from the screen, Panettiere had been open about difficult periods in her personal life.

She previously discussed struggles with alcohol and opioid addiction and had spoken publicly about receiving treatment. She also talked about experiencing postpartum depression after the birth of her daughter, Kaya, whom she shares with former professional boxer Wladimir Klitschko.

Those struggles became an important part of Panettiere’s story as she attempted to rebuild her health and career.

Her death at only 36 stunned fans who had watched her grow from a child actress into one of television’s most recognizable stars.

Now investigators are trying to determine exactly what happened during her final hours.

According to TMZ, the DEA is involved as authorities attempt to trace the suspected drugs and determine whether a fentanyl-laced pill contributed to her death.

But the most important piece of evidence remains outstanding.

Until toxicology testing is completed, the theory that Panettiere died after taking fentanyl-laced oxycodone remains just that — an investigative theory, not her officially confirmed cause of death.