The Drug Enforcement Administration (DEA) has reportedly joined the investigation into the untimely death of actress Hayden Panettiere at the age of 36.

According to Page Six, law enforcement officials confirmed that “the DEA is working alongside the Greenville Police Department and the coroner’s office to investigate the actress’ death on Sunday, and that it may be the result of a drug overdose.”

According to 911 audio, Panettiere reportedly died after going into cardiac arrest during a possible overdose at her rented apartment in South Carolina, per the Daily Mail.

In audio of a 911 call made at 1.51pm yesterday, a female dispatcher described the 36-year-old Heroes and Nashville star as suffering a ‘cardiac arrest.’

A few moments later, a male dispatcher could be heard saying that Panettiere had suffered a suspected overdose at the home in Greenville.

The Greenville County Coroner later indicated that Panettiere had “no signs of trauma that would have contributed to the death.”

An unnamed source later indicated to TMZ that the nasal medication Narcan, which is used to treat opioid overdoses, was found in a mattress at the time of her death.

“It is still unclear if that Narcan had been used to try and revive Panettiere,” noted the Daily Mail.

At the time of her death, Panettiere had been with her boyfriend, Brian Hickerson, and his brother, Zach.

“According to a police report obtained by Page Six, Brian had shown officers a ‘bag of medication’ she had been taking,” Page Six added. “While it’s unclear what the substances were, the ‘Ice Princess’ star’s hairdresser and good friend, Erick Orellana, exclusively told Page Six that Panettiere suffered from intense back pain.”

Panettiere’s death comes several months after she released her memoir, This Is Me: A Reckoning, in which she discussed the many struggles that plagued her going back to childhood. As Variety detailed at the time:

One of Panettiere’s more shocking revelations from her book is her memory, from when she was 18 years old, of being lured by friend of hers into a room and told to get in bed with a famous male actor who was naked. She shared the story, which she also recounts in her book, on a recent episode of the “On Purpose With Jay Shetty” podcast.

“Even though I felt I could make healthy decisions, safe decisions [at that age], I wasn’t capable of being fully aware of what was going on around me,” Panettiere said. “It wasn’t until I found myself in predicaments that I realized my perspective completely shifted and I realized I was in danger. By the time I realized I was in danger, I was quite literally out to sea.”

In the book, Panettiere also opens up about the “heartbreaking” decision to give up custody over her daughter, her experience with postpartum depression and her struggle with alcoholism — all issues that she says began to mirror the storyline of Juliette Barnes, the troubled singer she was playing on “Nashville” at the time.

Despite her past issues, in the weeks leading up to her death, Panettiere appeared hopeful and at peace, with her final Instagram post on July 27 celebrating “good times and good friends.”