Sondra Locke, who got an Oscar nod for supporting actress in her debut film appearance in “The Heart Is a Lonely Hunter,” died on November 3 at the age of 74. Her death was confirmed by the Los Angeles County Public Health Department.

According to a death certificate obtained by The Associated Press, Locked died in her Los Angeles home of cardiac arrest caused by breast and bone cancer. Authorities were contacted immediately, but her death was not made public until Thursday, when RadarOnline first reported it. It’s unclear why it took nearly six weeks to become public.

The blond, waifish actress had a dazzling film debut in Robert Ellis Miller’s The Heart Is a Lonely Hunter, winning an Academy Award nomination for her portrayal of adolescent Mick Kelly alongside Alan Arkin (1968).

Clint Eastwood, who initially cast Locke in “The Outlaw Josey Wales,” had a rocky relationship with her for more than a decade.

After they got together, Locke co-starred in practically all of Eastwood’s Warner Bros. films, including The Gauntlet (1977), Every Which Way But Loose (1978), Bronco Billy (1980), Any Which Way You Can (1980), and Sudden Impact (1983), with the actor directing all but two of them.

In 1968, she was nominated for an Academy Award for best supporting actress for her performance in an adaptation of Carson McCullers’ novel The Heart Is a Lonely Hunter. It was Sondra Locke’s debut feature film.

“I had never been on a movie set,” she told Variety in 1978, “but it was like coming home.”

She received critical acclaim for the role, as well as nominations for a Golden Globe and an Oscar. Ruth Gordon received both honors for “Rosemary’s Baby.”

She began directing in 1986 with “Ratboy,” followed by “Impulse,” 1995’s TV movie “Death in Small Doses,” and the independent feature “Do Me a Favor,” starring Rosanna Arquette.

Locke’s fairytale life came to an end in 1989, when Eastwood broke up with her, she later wrote. The locks were changed, and her belongings were deposited outside a house she assumed Eastwood had given her as a present.

Locke filed a palimony complaint against her 14-year domestic partner the same year. The resulting settlement included a three-year, $1.5 million deal for her to create and direct pictures at Warner Bros. (At the time she agreed to the arrangement, she was also going through chemotherapy after a double mastectomy.)

In 1990, Locke had a double mastectomy. In 1997, her book “The Good, the Bad, and the Very Ugly – A Hollywood Journey” was released.

“I try to cover the good years as well as the bad and the ugly,” Locke said. “Also, that in even the worst ugly things there can sometimes be a lot that will make you a better person.’’