An investigation has been launched into the death of beloved actress Hayden Panettiere after an autopsy found “no signs of trauma”.

A representative for the mother-of-one had died at the age of 36 on Sunday evening, local time.

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The Greenville County Coroner’s Office, in South Carolina, later that day said Panettiere’s cause of death remains pending further investigation.

An autopsy was completed Monday, the statement added, and “no signs of trauma were discovered that would have contributed to the death.”

The coroner’s office said emergency services had been called to an apartment complex regarding a “reported cardiac arrest”. Police said the call came from an acquaintance of the actor.

“Panettiere was found unresponsive inside the residence, where she had been temporarily staying,” the coroner’s office said.

Police have launched an investigation into the sudden death of Heroes star Hayden Panettiere. Credit: Matt Sayles/AP

Advanced cardiac life support measures were initiated, but resuscitation efforts were unsuccessful and. Panettiere was pronounced deceased at 2.32pm local time.

Officials were heard on dispatch audio discussing an “overdose”, according to People.

“The case is under investigation by the Greenville Police Department in conjunction with the Greenville County Coroner’s Office,” police said on Sunday.

Preliminary investigations have not indicated any signs of foul play or suspicious circumstances, police added.

Panettiere opened up about her struggles just months prior to her death, revealing her journey with postpartum depression and addiction.

Emergency services were heard on dispatch audio discussing an ‘overdose’ after Panettiere suffered a cardiac arrest. Credit: Evan Agostini/AP

She rose to international fame playing cheerleader Claire Bennet in the hit sci-fi series Heroes from 2006 to 2010.

She is survived by her a daughter, Kaya, with Ukrainian boxing champion Wladimir Klitschko.

“It is with profound sadness that we share the tragic passing of our beloved Hayden,” her representative said.

“She was an incredible light and a force of nature who brought immeasurable love and joy to all who knew her — and to the millions who watched her onscreen.

— with NBC