Mariska Hargitay in Beverly Hills, Calif., in June 2025. In a new HBO documentary made by the “Law & Order: SVU” star, Hargitay examines her own clouded origins and the mother she barely knew: Jayne Mansfield. (Kobe Wagstaff/The New York Times)

Mariska Hargitay was at home, and she was sprinting up the stairs, bounding between the corners of her very full life. I had to hustle to keep pace.

She checked in with her oldest son — home from his first year at Princeton University — and supervised the setup of an engagement party she was hosting for her goddaughter. Gardeners buzzed about the terraces of her Manhattan penthouse. She apologized for the noise.

Her latest obsession, a family heirloom grand piano, dominated the living room, with a custom “M” bench, courtesy of her husband, actor Peter Hermann (“Younger”). “That’s my next thing — I’m going to learn to play soon,” Hargitay vowed.

Another dash and we were on the floor below, a warren of cozy offices, painted in jewel tones, with overstuffed couches as well as muscular art by Annie Leibovitz. Tucked on a bookshelf were some of Hargitay’s awards. She has earned Emmys for playing Olivia Benson, the beloved “Law & Order: SVU” hardass, and for producing the 2017 documentary “I Am Evidence,” about the backlog of rape kits.

‘My Mom Jayne Debuts’ on HBO on June 27

This is where Hargitay had conceived, edited and even shot some of her newest and perhaps most life-altering project, the documentary “My Mom Jayne.” It’s at once an unflinching portrait of her mother, the 1950s star and pinup Jayne Mansfield, who died when Mariska was 3; an homage to her father, bodybuilder-actor Mickey Hargitay; and an investigation into her own clouded and secretive origins.

Directing the film, which will air June 27 on HBO, and proclaiming her story has unlocked something profound for Hargitay, 61.

“I am so clear now about the truth,” she said. “This big haze came off — a veil of fear. And now I just feel so much at peace. It’s like a miracle to me to feel this way.”

“You know, there’s so much pain left in the unsaid. And I just wanted to say it,” she added. “I’m not scared. I can be more Olivia Benson now.”

The documentary turns the lens on what Hargitay called her “bumpy ride” as she unpacks her history. Almost in real time, she unearths family mysteries and constructs a relationship with a parent she has no memory of, even as Mansfield’s traumatic end — a fatal car crash that Hargitay and two brothers survived — and foiled Hollywood ambitions defined her daughter’s path.

Mickey Hargitay, Who Died in 2006, Isn’t Her Biological Father

Figuring out how to be a woman in the public eye; grappling with celebrity, industry and motherhood; fighting expectations; facing the shame and release that overlaid, somehow, with her portrayal of Olivia Benson and her work as an advocate for survivors — all of that ended up onscreen. She wove it into a “Law & Order”-esque narrative that ends with the public revelation that Mickey Hargitay, who died in 2006, is not her biological father.

“Sometimes keeping a secret doesn’t honor anyone,” she says in the documentary.

Hargitay has known Nelson Sardelli, a singer whose brief relationship with her mother led to her birth, for some 30 years. But she had never asked him the kind of pointed questions she did in her very first interview for the film. More than a touch of Captain Benson’s steely-jawed scowl comes out onscreen, when she asks him: Why didn’t you acknowledge me when I was a child?

Benson is the longest-running character on the longest-running prime-time drama in TV history. Since she first appeared on the procedural in 1999, as a detective who’s driven to seek justice for victims of sexual violence, women have sought out Hargitay to share their own experiences of abuse and assault.

For so many, the character has stood as a source of strength. That Hargitay’s performance was based in her own shadows is a bombshell, too. Last year, she disclosed that a man had raped her when she was in her 30s — a fact it took her years to acknowledge, even to herself.

“We portray finding the truth and going to these dark places,” said Christopher Meloni, who played her “SVU” partner Elliot Stabler. Deep discoveries happen “when you’re close to the flame. And it’s a real flame for her.”

Hargitay didn’t learn the truth about her parentage until she was an adult. But growing up, she said, “I just always knew something was up.”

Mansfield Died at the Age of 34 in 1967

Mansfield, who was only 34 when she died in 1967, had five children from three marriages. The most notable husband was Hargitay, a Hungarian-born athlete. In their heyday, they were an accessible It Couple, frequently performing together.

Mansfield was a classically trained musician, spoke four languages and studied acting before her breakout role on Broadway in “Will Success Spoil Rock Hunter?” She reprised it for the 1957 movie, and went on to a few more high-wattage parts. But her acting talents were overshadowed by the entertainment world’s interest in her buxom figure. She was marketed as a Marilyn Monroe-dupe, eventually making her living with a sometimes tawdry nightclub act.

After Mansfield’s death, her family rarely told casual stories about her, Hargitay said. Mostly, what her father imparted was that Mansfield “listened to the wrong people, and that they tried to mold her and make her,” Hargitay said. She absorbed that lesson fully.

“The reason that I’m like the way I am is because I learned from her,” Hargitay said of her mother. “I learned what not to do. I learned to not let anyone tell me — that I decide.”

Her steely will also came from Mickey Hargitay. “He’s the one that taught me about perseverance,” she said.

Her parents had split before she was conceived, then reconciled when Mansfield was pregnant, then split again. When her mother died, Mickey Hargitay and his wife, Ellen Siano, raised her, alongside her older brothers Mickey Jr. and Zoltan, his biological children with Mansfield. Mansfield’s relationship with Sardelli was public in the ’60s, and some of her siblings were aware of her split parentage, Hargitay said. But they never discussed it.

She and Sardelli are now close; they spent Father’s Day together, and he wept as Hargitay told him she was ultimately grateful for the choices he’d made decades ago.

And she still refers to Mickey as her father. She initially worried that making the documentary would be betraying him, she said. Then she realized: “This is the biggest thank you. This is saying, ‘I am your daughter.’ I’m screaming it from the rooftops that you are the best dad and I’m loved, and everything that’s strong and good and moral about me — it’s because of him.”

Of her siblings, Hargitay is the only one who found her career in front of the camera. “It’s connection for me,” she said. “That’s what ‘SVU’ is — it’s not just a show. It’s a conversation.”

Hargitay’s Foundation Supports Rape Survivors

But the intense scripts and the onslaught of other people’s stories took a toll. “I’ve had my fair share of secondary trauma,” she said. She also felt, she said, a responsibility to help. She trained to be a rape crisis counselor and in 2004 started the Joyful Heart Foundation, which supports survivors.

“I always cite her as an example of a woman who inspires by her public role and presence,” said her friend Gloria Steinem, the feminist icon and an “SVU” watcher.

Another friend, journalist Diane Sawyer, was struck by Hargitay’s bravery. “She just makes everything possible, because she’s strong and generous,” she said.

Perhaps more than at any other moment in her life, Hargitay feels empowered and free. Her attitude, she told me, is “I can’t wait to see what I do next.”

That was one more thing that welded her to her mother, she realized — their appetite for a big, uncompromising life.

“She was amazing,” Hargitay said. “That’s been the gift: I got to see her. I got to have so many moments with her. And we got to make a movie together.”