GREENVILLE, S.C. — Police in Greenville, South Carolina, have closed their investigation into the death of actress Hayden Panettiere, ruling it an accidental overdose after a coroner's report found a combination of fentanyl and four other substances in her system.

The Greenville County Coroner's Office identified the cause of death as the toxic effects of fentanyl, 4-ANPP, alprazolam, methocarbamol and quetiapine, according to CBS News. The autopsy found no signs of trauma that contributed to her death.

What happened

Panettiere, best known for her roles in Heroes and Nashville, was found unresponsive on Aug. 16 at a South Carolina apartment complex where she had been staying. A family source told reporters the coroner's report noted she had been released from a drug rehabilitation center in Malibu, California, not long before her death.

NO SIGNS OF TRAUMA CONTRIBUTED TO HER DEATH

Greenville police said this week that the death has been ruled accidental and that their investigation is now closed, with ABC News reporting that no charges have been filed against anyone in connection with her death.

A federal inquiry's status unclear

The Drug Enforcement Administration had separately been examining whether Panettiere obtained illicit or counterfeit pills before she died; reporting so far has not confirmed the outcome of that federal inquiry. Panettiere, who rose to fame as a child actress before starring as cheerleader Claire Bennet on Heroes and later as a country singer on Nashville, had spoken openly in past interviews about her struggles with substance abuse and postpartum depression.