The television actor Allison Mack, who pleaded guilty for her role in a sex-trafficking case tied to the cult-like group NXIVM, has been released from a California prison, according to a government website.

Mack, best known for her role as a young Superman’s close friend on “Smallville,” was sentenced to three years behind bars in 2021 after pleading guilty two years earlier to charges that she manipulated women into becoming sex slaves for NXIVM leader Keith Raniere.

Online records maintained by the Federal Bureau of Prisons said Mack, 40, was released Monday from a federal prison in Dublin, Calif., near San Francisco. Her release was first reported by the Albany Times-Union.

Mack avoided a longer prison term by cooperating with federal authorities in their case against Raniere, who was ultimately sentenced to 120 years in prison after being convicted on sex-trafficking charges.

Mack helped prosecutors mount evidence showing how Raniere created a secret society that included brainwashed women who were branded with his initials and forced to have sex with him.

In addition to Mack, members of the group included an heiress to the Seagram’s liquor fortune, Clare Bronfman; and a daughter of TV star Catherine Oxenberg of “Dynasty” fame.

Mack would later repudiate Raniere and express “remorse and guilt” before her sentencing in federal court in Brooklyn, N.Y.