The AP obtained a copy of the report, and says Kidder, 69, died as the "result of a self-inflicted drug and alcohol overdose".
When Margot Kidder died in May, she was remembered as the actress who brought the fictional reporter Lois Lane to life in a series of blockbuster Superman movies in the 1970s and '80s. The coroner did not specify which drugs she took, TMZ reported.
Kidder was diagnosed with bipolar disorder and eventually suffered a public nervous breakdown in 1996 after facing several career setbacks in the early 1990s, including a auto crash which resulted in her being paralyzed for two years.
Now, nearly three months after Kidder's body was found by a friend in her Livingston, Montana home, a coroner there has ruled her death a suicide. "It's important to be open and honest so there's not a cloud of shame in dealing with this".
Results, points after Xfinity race at Watkins Glen
Pearn was pivotal past year at The Glen when the No. 78 won a strategic fuel mileage race. "Nothing surprises me anymore". Suarez is fighting for a Playoff berth, now three spots out of the postseason at 18th in the series standings.
Kidder was married to novelist Thomas McGuane with whom she had a daughter, Maggie. I want what I know about her to be out there because it was glorious. She's also an activist for many causes. The world mourned the loss of chef, celebrity chef, Anthony Bourdain and fashion designer, Kate Spade this past summer as well.
According to IMDB, Kidder had two projects in pre-production at the time of her passing.
And she was known for her work as a mental-wellness advocate, in part because of her own struggles with mental health.
McGuane urged people with mental illness to seek help.
"It's a very unique sort of grief and pain". She went on to appear in small films and television shows until 2017, including an appearance on R.L. Stine's The Haunting Hour.