United Kingdom, Aug. 24 -- Hayden Panettiere's mother has questioned the account of her daughter's final hours as investigators continue trying to establish what caused the Heroes and Nashville actor's death at 36.

Lesley Vogel, 70, said she has doubts about the timeline surrounding Hayden's death on August 16 at a residence in Greenville, South Carolina.

Hayden's on-again, off-again boyfriend Brian Hickerson, 37, and his brother Zach Hickerson were at the property when she was found unresponsive, according to a police report.

Authorities have said there were no signs of trauma or foul play, and an official cause and manner of death have not yet been determined.

According to Lesley's account to the Daily Mail, Brian told police he lef...