NEW YORK (AP) — TV actor Allison Mack, who played a key role in the cultlike group NXIVM, has surrendered to a California prison to serve her sentence in a New York case against the group’s spiritual leader.

Mack, best known for her role as a young Superman’s close friend on “Smallville," was the third person associated with NXIVM to be sentenced to three years in jail in June, when a federal judge in Brooklyn ordered her to surrender by late September and pay a $20,000 fine for her role. She had previously pleaded guilty to the charges she manipulated women into becoming sex slaves for NXIVM leader Keith Raniere, and had been under house arrest in California since her arrest in April 2018.

With her plea, Mack admitted she gave “seduction assignments” to several women in the secret NXIVM sub-group DOS, which stands for a Latin phrase loosely translated as “master over the slave woman.” Women in DOS were told they would be joining a secret women’s sorority.

A prison website showed Thursday that she had entered a low-security facility in Dublin, California, about 35 miles east of San Francisco.

Despite sentencing guidelines ranging from 14 to 17 1/2 years, Mack, 39, dodged a longer prison term by becoming a government cooperator in the federal case and prosecutors recommended she be given less time due to her “substantial assistance” against Raniere and other NXIVM co-conspirators. Mack provided emails, documents and recordings to the government. Prosecutors credited her with helping them mount evidence showing how Raniere created a secret society of brainwashed women who were branded with his initials.

Since pleading guilty, Mack has received her associate’s degree, enrolled in courses at the University of California, Berkeley and become active in a local church, according to her attorneys.

Raniere was sentenced last year to 120 years in prison for his conviction on sex-trafficking charges.