I vividly remember entering the California Institution for Women for the first time in 2001. As the prison guard slammed the gate behind me, I wondered if I had made the right decision to become a volunteer for an inmate support group. But my nerves were eased by a woman who introduced herself as “Krenny.” Welcoming me into the group, she seemed quiet and insecure — yet also exuded an inner strength. I had no idea how she got here and didn’t ask.

It was only several years later, while documenting the support group for a documentary film, “Sin by Silence,” that I learned Krenny’s full name: Patricia Krenwinkel. I was astounded. She was one of the infamous Charles Manson followers, convicted of seven murders. She eventually approached me to go on camera with her story.

In this Op-Doc video, Ms. Krenwinkel provides her first on-camera interview since 1994, reflecting on her life before and after Manson. This week is the 45th anniversary of her crimes.

In 1969, at age 21, Ms. Krenwinkel was a member of Mr. Manson’s cult in Los Angeles. His group, which he called the “Family,” included more than a dozen men and women who adhered to a bizarre mixture of hippie culture and apocalyptic paranoia. Seeking to inspire a race war, Manson ordered Ms. Krenwinkel and other members of his group to commit a series of murders. Over the course of two nights, they savagely murdered seven people, inflicting more than 130 stab wounds. One of them, the actress Sharon Tate, was eight and a half months pregnant. At their trial, the women shamelessly admitted their crimes and flaunted their allegiance to a leader they loved, but who clearly controlled their minds.