The Drug Enforcement Administration has joined the investigation into Hayden Panettiere’s death, according to ABC News.

The DEA is entering a joint effort with South Carolina’s Greenville Police Department and the local coroner’s office, according to TMZ.

Panettiere died Sunday night at age 36. The official cause of death has not yet been determined. In her 2026 memoir “This Is Me: A Reckoning,” Panettiere went into detail about her years-long struggles with drug and alcohol addiction.

After news broke of Panettiere’s death, tributes from across Hollywood came pouring in online. On Wednesday, Jack Coleman, who played her father on “Heroes,” shared an emotional tribute on Instagram.

“I’m heartbroken. I couldn’t begin to put my thoughts into words until now, and they will be inadequate,” Coleman wrote. “I’ve loved Hayden since day one of the pilot of ‘Heroes,’ 20 years ago, when she introduced herself by shouting ‘daddy’ and throwing her arms around me. From that day on, she called me daddio. She was Haydini, because she was a magician.”

Christy Carlson Romano, the Disney Channel star who played Ren Stevens on “Even Stevens” and voiced the titular teen spy on “Kim Possible,” likewise shared a remembrance for Panettiere on Wednesday. In an essay for Elle, she compared the trauma of childhood fame to Chronic Traumatic Encephalopathy (CTE), a brain disease caused by repeated hits to the head.

“The former child actor exists in a category the world does not know how to hold,” she wrote. “We are children when the public wants to feel protective of us, professionals when the industry wants to profit from us, and spoiled celebrities when we eventually show symptoms of having been both… Early fame is like CTE. Not as a diagnosis. As a way of thinking about repeated impact. We now have language for youth sports: protocols, helmets, parents worried about concussions. But we have almost no language for what happens when stress, scrutiny, rejection, adult pressure, and the collapse of privacy become the architecture of a childhood.”