Mariska Hargitay has revealed a long-held family secret: the truth about her biological father.

The actress, whose mother was Jayne Mansfield, had believed for years that her father was Mickey Hargitay, the Hungarian bodybuilding champion who became an actor. He married Mansfield in 1956.

When Mariska was only 3, she and her mother were involved in a tragic car accident that killed Mansfield instantly. Mickey raised their three children after Mansfield died.

“He was my everything, my idol. He loved me so much, and I knew it,” she told Vanity Fair. “I also knew something else — I just didn’t know what I knew.”

In fact, she didn’t know the truth until she was in her 20s. During a brief time in 1963-64, Mansfield filed for divorce from Mickey and began dating Italian entertainer Nelson Sardelli. However, Mickey and Mansfield reconciled months before Mariska’s birth.

Mariska had always believed something felt different between her and her siblings (Jayne Marie, Zoltan and Mickey Jr.), and when she was in her 20s, she saw a photo of Sardelli that confirmed her feelings. She says she knew right away that he was her biological father. When she asked Mickey, he denied it, and they never spoke of it again.

When she was 30, Mariska traveled to Atlantic City to see Sardelli perform. After she introduced herself, she said, he became emotional and told her, “I’ve been waiting 30 years for this moment.”

“I went full Olivia Benson on him,” she said of her reaction. “I was like, ‘I don’t want anything, I don’t need anything from you. … I have a dad.’ There was something about loyalty. I wanted to be loyal to Mickey.” (Mickey died in 2006.)

She added that she struggled with “knowing I’m living a lie my entire life.”

Mariska ultimately became close with Sardelli and his daughters. She also realized that her mom went back to Mickey because she felt that being with him would be better for her daughter.

“I grew up where I was supposed to, and I do know that everyone made the best choice for me,” she said. “I’m Mickey Hargitay’s daughter — that is not a lie.” 

The Law & Order: SVU star also opens up about this revelation in her new documentary My Mom Jayne, which premiered Saturday at the Cannes Film Festival and debuts June 27 on HBO/HBO Max.