A coroner has revealed that Carrie Fisher died of sleep apnea and other causes after she become unresponsive on a flight from London to Los Angeles in December.

According to the Associated Press, officials in the coroner’s office could not conclusively determine exactly which factors contributed to Fisher’s death, but found that she had taken drugs prior to her death and had clogged arteries in addition to suffering from sleep apnea.

It is unclear what drugs Fisher had taken and what role they played in her unexpected death. The Star Wars actress had been open about her struggles with mental health issues and drug addiction.

Fisher died in a Los Angeles hospital on December 27, and her mother, Debbie Reynolds, died one day later.

Feature Photo: Associated Press