A Greenville police officer who responded to the residence on Sunday afternoon was met by the brothers and then observed paramedics performing CPR on an unresponsive woman, the report states.
"The patient did not seem to have any obvious physical reasons to be unresponsive," the officer notes. After attempting lifesaving measures, the emergency workers declared Panettiere dead.
The Greenville County Coroner's Office said the cause of death is pending further investigation.
An autopsy found no signs of trauma, and police said officers saw no signs of foul play.
The former child star, who soared to fame in the TV shows Heroes and Nashville while enduring struggles with alcohol addiction and depression, would have turned 37 on Friday.
Panettiere and Brian Hickerson had been in a tumultuous relationship for years, with allegations the 37-year-old aspiring actor physically abused her.
He was charged in 2020 with multiple counts of felony abuse, and he pleaded no contest to two counts of injuring a spouse or partner and served a short time in jail due to the case. He was sentenced to four years of probation and anger management and Alcoholics Anonymous sessions.
He completed the terms and recently asked a judge to reduce his conviction to misdemeanours; that request was denied by a Los Angeles judge.
The police report, which is heavily redacted, said the responding officer first spoke with Zach Hickerson, who said the unresponsive woman was his brother's girlfriend.
"I observed Zach to be very emotional while EMS were working on Hayden. Brian did not become emotional until EMS declared her officially deceased," the officer said.
After Panettiere was declared dead, the officer escorted the brothers out of the apartment. The officer spoke with Brian "more in depth," but the details of that conversation are redacted in the police report.
Also redacted is a list that of medications that Panettiere had been taking.
In her book, Panettiere described lifelong scars from her early fame, and acknowledged being addicted to alcohol and enduring postpartum depression after the birth of her daughter, Kaya, with Ukrainian boxer Wladimir Klitschko in 2014.
Panettiere's daughter, now 11, began living with Klitschko full-time in Ukraine when she was two. At the time, the actor was struggling with mental health and addiction. She entered rehab in 2015, while filming Nashville.
In a statement, Klitschko said he will make sure their daughter always remembers her mother.
"She built an incredible career through immense talent, while also facing the darker sides of a very demanding industry," Klitschko said on Instagram.
"Nothing will erase the times we shared or the place she had in our lives."
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