Anne Heche died due to smoke inhalation and thermal injuries, the Los Angeles County Medical Examiner-Coroner has said.
The Hollywood actress’ death was ruled an accident, according to a coroner’s report seen by US media outlets.
It comes after she was “peacefully taken off life support” on Sunday, nine days following the car crash in which she suffered a “severe anoxic brain injury”.
Heche’s vehicle collided with a residence in the Mar Vista area of Los Angeles and became “engulfed in flames”.
The report also reportedly cited a “sternal fracture due to blunt trauma” as another “significant condition” contributing to her passing.
Earlier on Sunday, the Los Angeles Police Department (LAPD) said they had concluded their investigation into Heche’s serious car crash.
“As of today, there will be no further investigative efforts made in this case,” police said in a statement.
Announcing her death, Heche’s family shared a statement with PA praising her “extraordinary talent” and “generous spirit”.
“She saw spreading kindness and joy as her life’s work – especially moving the needle for acceptance of who you love,” the statement read.
“She will be remembered for her courageous honesty and dearly missed for her light.”
Heche dated US talk show host Ellen DeGeneres from 1997 to 2000.
Posting to her social media after Heche was declared legally dead, DeGeneres, 64, wrote: “This is a sad day.
“I’m sending Anne’s children, family and friends all of my love.”