Los Angeles – The death last year of actor Carrie Fisher, best known for her role as Princess Leia in the “Star Wars” franchise, was due to sleep apnea and other causes, the Los Angeles County Coroner’s Office said in a statement on Friday.

Fisher died aged 60 on Dec. 27, four days after she became unresponsive on a flight from London to Los Angeles and was rushed to a hospital.

Fisher was a mental health advocate who spoke about her struggles with bipolar disorder and cocaine addiction. Aside from her film work, she was also popular as a writer and humorist and her memoir “The Princess Diarist” was released a few weeks before she died.

The Los Angeles County Coroner’s Office conducted an examination of her body on Dec. 30 and has since found she died of sleep apnea and “other undetermined factors,” the coroner’s statement said.

Fisher also had atherosclerotic heart disease and had used drugs, the statement said, but noted the significance of these factors in relation to her demise had not been ascertained.

Carrie Fisher came from a Hollywood family, as the daughter of actor Debbie Reynolds and singer Eddie Fisher.

The day after Carrie Fisher died, Reynolds suffered a stroke and died, aged 84.

Born in Beverly Hills, Carrie Fisher got her show business start at age 12 in her mother’s Las Vegas nightclub act. She made her film debut as a teenager in 1975 comedy “Shampoo,” two years before her breakthrough in the first “Star Wars” movie.

After undergoing treatment in the mid-1980s for cocaine addiction, Fisher wrote the bestselling novel “Postcards from the Edge,” about a drug-abusing actress forced to move in with her mother. The book was later adapted into a film starring Meryl Streep and Shirley MacLaine.