Actress Anna "Patty Duke" Pearce, who won an Oscar for her role as Helen Keller in 1962's "The Miracle Worker," has died at 69.

Her agent, Mitchell Stubbs, confirmed to CBS News that the actress died on Tuesday morning from sepsis stemming from a ruptured intestine.

"She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon," it said in the statement. "She will be greatly missed."

Duke made her Broadway debut in "The Miracle Worker" with Anne Bancroft in 1959; Duke won the Theatre World Award as "Most Promising Newcomer" at the age of 12. Later, the two actresses reprised their roles in the film version and both won Oscars for their performances. Duke's Best Supporting Actress win made her the youngest Oscar winner in history at the time.

The actress also played identical cousins on the popular "Patty Duke Show" in the early 1960s, and also charted on Billboard's top ten with her song "Don't Just Stand There."

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The actress crossed over into darker material as Neely O'Hara in "Valley of the Dolls" in 1967, and appeared in various movies on both the small screen and big screen. Duke later returned to "The Miracle Worker" in a 1979 TV remake, this time playing Anne Sullivan; she won an Emmy for the role.

Duke was also the second woman to be elected president of the Screen Actors Guild, and also became a best-selling author for her memoirs "Call Me Anna" and "A Brilliant Madness," in which she wrote about her struggles with bipolar disorder.

The star remained active late in her career, appearing on "Glee" and most recently, Disney TV series "Liv and Maddie."