Mariska Hargitay’s dedication to “Law & Order: Special Victims Unit,” and its viewers, has taken her in a new but related direction.

Also a producer of the Wednesday NBC series on which she’s played New York police detective Olivia Benson for 19 seasons, Hargitay focuses on a subject the drama has covered — the many untested kits submitted by rape victims — by producing the HBO documentary “I Am Evidence,” premiering Monday, April 16. She appears early in the program, but directors Trish Adlesic and Geeta Gandbhir then turn the cameras toward victims and medical and legal professionals.

“I felt so overwhelmed and shocked by the statistics, and I was so outraged that it was this issue that was sort of swept under the carpet,” Hargitay says. “I started the Joyful Heart Foundation to put structure to my outrage about how society was treating survivors. Then in 2009, I found out about the rape-kit backlog from a study that was done by Human Rights Watch, and I couldn’t wrap my head around it. I thought it was the most staggering and shocking demonstration of how we regard these crimes.”

Calling herself “a documentary-film enthusiast” who educates herself by watching such works, Hargitay notes that in being an “SVU” star, “I have heard so many stories, and have been so privileged to witness so much firsthand, I just wanted to turn up the volume on those voices. Testing these kits sends a fundamental and crucial message to victims that they and their cases matter … and not testing the rape kits sends the opposite message.

“Our working title (for the documentary) was `Shelved,’ ” Hargitay adds, “conveying the idea that these are women’s lives sitting on shelves, the hundreds of thousands of untested rape kits. It’s been a profound and painful journey, but I’m so happy to give voice to people who need to have their stories told. They’ve been ignored for far too long, and it’s a travesty.”

Hargitay allows that her appearance in “I Am Evidence” was “a back-and-forth decision. Originally, I didn’t want to be in it, and (HBO) really felt we needed an entrance into the story … so they wanted me to introduce it, because I am so associated with this subject matter. I walk you through it, then you go.”

In terms of how closely her weekly role meets her philanthropy, Hargitay reasons, “I’ve been given this platform, and for so long, it was figuring out what to do with it. I feel so blessed to have met this character and this show, and to have been given this incredible opportunity. We all live to give back, and I’m lucky that I’ve found my calling.”