Charlize Theron admitted she nearly turned down her Oscar-winning role as real-life serial killer Aileen Wuornos in the 2003 film “Monster.”

“I didn’t think I could do it at first,” the 43-year-old told Marie Claire Australia in their June 2019 issue. “The thing that convinced me ultimately was that I had never had — and I get emotional thinking about it — I never had somebody believe in me like that before. I was always the person who would go into audition after audition after audition and lay myself on broken glass and not get the part. And all of a sudden, this woman is sitting in front of me, and she’s like, ‘You have to. You’re the only person who can.’”

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The star said she’s still stunned that filmmaker Patty Jenkins strongly believed she could bring the controversial figure to life on the big screen.

“I was blown away by that,” said Theron. “It’s super emotional because I don’t think a lot of women get an opportunity like that… I feel like when you work with people who believe in you fully like that, if you have that kind of faith in me, I will do anything for you.”

Wuornos, a hitchhiking prostitute in Florida who killed six men was executed in 2002 at age 46. She became the 10th woman executed in the United States since capital punishment resumed in 1977. “Monster” was released a year later.

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Theron previously told SplicedWire.com she initially didn’t know who Wuornos was before she took on the role.

Aileen Wuornos was recently the subject of a true crime documentary on Oxygen. (AP)

“… This was the first time, I think in my entire career when by the second-to-last page [of the script], I still didn’t know how I felt about the character,” she explained at the time. “I also thought it was interesting because I don’t think it’s really a common thing for writers to write conflicted female characters. The guys always get to play those great gray characters, and somehow women always tend to be black and white. So I knew this was also something very unusual and might never come my way again. Those movies just don’t get made.”

Theron reportedly gained 30 pounds to play Wuornos, a major transformation for the South African model.

“[Aileen] wrote in a letter that even though she was a prostitute and would do pretty much anything, the one thing she wouldn’t do was take her shirt off,” said Theron. “I don’t think she liked her body. I think her body represented a lot of demons for her. So from reading that, I said, ‘Patty, I think I’m going to put on some weight.’ We never discussed it like this big thing, like so aim — ‘We’re gonna gain 30 pounds.’”

“It wasn’t about getting fat,” Theron continued. “Aileen carried scars on her body from her lifestyle, and if I’d gone to make this movie with my body — physically I’m very athletic — I don’t know that I would have felt the things Aileen felt with her body. It was about getting to a place where I felt closer to how Aileen was living. I didn’t want to look at my body and see my natural muscle. That kind of thing would have thrown me off completely in trying to be her.”

The Associated Press contributed to this report.