The Los Angeles County Medical Examiners Office has officially declared that Carrie Fisher's tragic death was due to sleep apnea and other unknown contributors. The full autopsy report is set to release Monday, but "The manner of death has been ruled undetermined" is the official word from the coroner's statement.
Carrie Fisher's unfortunate passing happened on December 27th, 2016, several days after she experienced a heart attack after boarding a flight from London to Los Angeles and 3 days before the passing of her mother, Debbie Reynolds. Carrie was 60 years old. According to the coroner's report, she had sleep apnea and hardening of the arteries, but those factors may not have been the immediate cause of death.
As an avid proponent of mental health, Carrie was an inspiration to many people who struggle with mental disorders and was frequently very candid about her own battles with bipolar disorder, for which she relied on several different medications, so it's no surprise that multiple substances were found in her system, but the investigators did not conclude that any medication or other substance was directly responsible for her heart attack.
UPDATE: Per Variety, Fisher's autopsy report has confirmed that she had cocaine, methadone, heroin and ecstasy in her system upon the time of her death. However, according to the relevant segment from said report, "Based on the available toxicological information, we cannot establish the significance of the multiple substances that were detected in Ms. Fisher’s blood and tissue, with regard to the cause of death."
Her daughter, Billie Lourd, released an emotional, yet encouraging, statement to People addressing the coroner's findings"
“My mom battled drug addiction and mental illness her entire life. She ultimately died of it. She was purposefully open in all of her work about the social stigmas surrounding these diseases.
She talked about the shame that torments people and their families confronted by these diseases. I know my Mom, she’d want her death to encourage people to be open about their struggles. Seek help, fight for government funding for mental health programs. Shame and those social stigmas are the enemies of progress to solutions and ultimately a cure. Love you Momby.”
As Princess (and General) Leia in the Star Wars saga, Fisher's many fans got to mourn the passing of the star at 2017's Star Wars Celebration, where multiple tributes were made to the late writer and actor's legacy, including a touching video from the 40th Anniversary panel, as well as a Mark Hamill hosted panel serving solely as a tribute to his former co-star and dear friend of 40 years.
Fisher had completed all her footage for The Last Jedi, in which she's said to have a significant role (and even worked on the script), but it's not clear how Lucasfilm will handle her presence in Episode IX, where she may have had an even more significant role.
Despite her unfortunate passing, Fisher has been immortalized not only as a Star Wars legend, but also as a talented writer and beacon for mental health awareness, and her memory will live on with her fans for generations.
Update Source: Variety