DEA Joins Investigation Into Hayden Panettiere's Death

The Drug Enforcement Administration has joined the investigation into the death of actress Hayden Panettiere, according to sources familiar with the matter.

The Greenville City Police Department in South Carolina remains the lead agency on the case, with the DEA now assisting. ABC News has reached out to representatives of Panettiere for comment.

Panettiere, known for roles in "Ice Princess," "Heroes" and "Nashville," died Sunday at a private residence on Easley Bridge Road in Greenville. She was 36.

The DEA's involvement comes a day after Greenville police released a report detailing the scene where Panettiere was found. According to the report, an officer responded to an EMS call for an unresponsive individual and found that Panettiere had been with her on-again, off-again boyfriend Brian Hickerson and his brother, Zack Hickerson, at the time of her death.

The report says it remains unknown whether Panettiere was using drugs or alcohol when she died, though the responding officer noted that Brian Hickerson showed police a bag of medication Panettiere had been taking. Officials and the coroner's office both responded to the scene to conduct their own investigations.

The coroner's office said Monday that Panettiere's official cause and manner of death "remain pending further investigation and the completion of additional studies."

Before her death, Panettiere had spoken openly about personal struggles dating back to her time as a child star. She released a memoir in May, "This Is Me: A Reckoning," which its publisher described as offering "a rare and intimate glimpse into her life behind closed doors," addressing postpartum depression, addiction and recovery, trauma, domestic abuse and loss.

Besides "Ice Princess," "Heroes" and "Nashville," Panettiere appeared in "Remember the Titans," "Raising Helen" and several "Scream" films. She is survived by her daughter, Kaya, whom she shared with her ex-fiancé Wladimir Klitschko.