Skye McCole Bartusiak

Skye McCole Bartusiak -- who played Mel Gibson's daughter in the 2000 movie "The Patriot" -- died from an accidental mix of pain killers and muscle relaxers ... and it looks like she may also have been huffing ... TMZ has learned. According to the Harris County Institute of Forensic Sciences, the…

1:00 PM PST: Skye reportedly had been suffering from seizures and on Saturday morning her boyfriend came home and found her sitting up in bed in her parents converted garage. The family believes she had a seizure and choked to death. Skye McCole Bartusiak -- who played Mel Gibson's daughter in the…