The investigation into the death of actress Hayden Panettiere has expanded to become a cross-country effort, spanning both Los Angeles and South Carolina, according to sources speaking to ABC News. The inquiry is now centering on the specific drugs that may have contributed to her passing and their origins.

Panettiere, celebrated for her roles in "Heroes," "Nashville," and "Ice Princess," was found unresponsive and in cardiac arrest on August 16. First responders attempted resuscitation at a residence in Greenville, South Carolina, but she was pronounced dead at the scene.

Sources close to the investigation revealed the widening scope and the specific focus on pharmaceuticals. The nature of the drugs involved and how they came into Panettiere's possession are now key areas of inquiry for law enforcement.

The expansion of the investigation suggests authorities are pursuing leads that extend beyond South Carolina, indicating potential connections or a wider network involved. This development underscores the complexity of the case and the seriousness with which officials are treating the circumstances surrounding her death.

Panettiere's career spanned several successful television shows and films, making her a recognizable figure in Hollywood. Her sudden death at 36 has prompted widespread reaction from fans and colleagues.

Details regarding the specific substances under scrutiny have not been publicly disclosed. Law enforcement agencies involved have not yet released official statements on the progress of the cross-country investigation.

This investigation is ongoing, and further details are expected to emerge as authorities continue to gather information and evidence across multiple jurisdictions.

The public awaits further information as the investigation seeks to provide clarity on the factors leading to the actress's untimely death.