Skye McCole Bartusiak, who played Mel Gibson's young daughter in The Patriot (2000), has died in her Houston home at 21, her mother confirmed on Sunday.
Helen Bartusiak told The Associated Press that the actress had been living in a garage apartment at her parents' home.
She was found dead in her bed by her boyfriend on Saturday.
Helen Bartusiak said that she attempted to resuscitate her daughter, but had failed.
She added that Skye had been a healthy 21-year-old, and did not drink or take drugs.
Her cause of death is not yet known by the family.
Bartusiak made her acting debut in the television miniseries Storm of the Century in 1999 and also had a role in 24 between 2002 and 2003.
She made her film debut in the The Cider House Rules in 1999 and starred opposite Michael Douglas in Don't Say a Word in 2001. Her most recent move was Sick Boy in 2012.
Bartusiak was best known for her role in Gibson's Revolutionary War epic The Patriot, where she played the daughter of militia leader Benjamin Martin.
The Patriot cast also included Heath Ledger, who died after an accidental overdose of painkillers and sedatives in 2008.
Additional reporting by AP