“Superman” actress Margot Kidder’s death has been ruled a suicide, according to the Associated Press.

Kidder’s daughter, Maggie McGuane, told the publication on Wednesday that she knew her mother had died by suicide when she went to her home in Livingston, Mont.

Kidder died in her sleep on May 13 from what Park County Coroner Richard Wood said in a statement was the result of “a self-inflicted drug and alcohol overdose.”

McGuane said she found relief knowing that the truth about her mother’s death was finally known to the public. She told the AP she believes it’s important to be open and honest about Kidder’s suicide so neither her nor her family faces a cloud of shame as a result.

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 car crash which resulted in her being paralyzed for two years.

Kidder rose to fame as Lois Lane alongside Christopher Reeve in the first “Superman” films. In addition to “Superman,” she also appeared in 1970’s “Quackser Fortune Has a Cousin in the Bronx” opposite Gene Wilder, 1973’s “Sisters,” “The Great Waldo Pepper” with Robert Redford, and 1979’s “The Amityville Horror.”