NEW YORK — TV actor Allison Mack, who played a key role in the scandal-ridden, cult-like group NXIVM, was sentenced to three years in prison Wednesday on charges she manipulated women into becoming sex slaves for the group's spiritual leader.

Mack — best known for her role as a young Superman's close friend on the series "Smallville" — had previously pleaded guilty to the charges and began cooperating against NXIVM leader Keith Raniere. Prosecutors credited her with helping them mount evidence showing how Raniere created a secret society of brainwashed women who were branded with his initials.

At her sentencing in Brooklyn federal court, Mack renounced the self-improvement guru.

"I made choices I will forever regret," she said, also telling the judge she was filled with "remorse and guilt."

"I am sorry to those of you that I brought into NXIVM," she wrote in a letter filed with the court last week. "I am sorry I ever exposed you to the nefarious and emotionally abusive schemes of a twisted man."

She reiterated her apologies to the victims in court on Wednesday: "From the deepest part of my heart and soul, I am sorry."

Mack wept at times while reading her statement to the court. U.S. District Judge Nicholas Garaufis told her he believed her apology was sincere, but said she deserved a serious sentence for using her celebrity to groom victims as "a willing and proactive ally" and "essential accomplice to Raniere's monstrous crimes."

Under advisory sentencing guidelines, Mack had faced between 14 and 17 1/2 years behind bars, but her defense team argued in court papers that probation or a sentence to home confinement was more appropriate. Prosecutors had agreed that any prison term should be below the guidelines range because of her cooperation.

"The NXIVM saga and the story of Ms. Mack's descent have been a tragedy for all involved. But that need not, and should not, be the end of the story for Allison Mack," her lawyers wrote in court papers.

A victim, Jessica Joan, rejected Mack's apologies, telling the judge the actor deserved no mercy.

"She can blame Keith all she wants but she is a monster cut from the same cloth," Joan said in court on Wednesday. "Allison Mack is a predator and an evil human being."

Mack, 38, was once part of the inner circle of Raniere, whose group attracted millionaires and actors among its adherents. Prosecutors said she became a "master" for "slaves" she ordered "to perform labor, take nude photographs, and in some cases, to engage in sex acts with Raniere."

As authorities closed in on Raniere, he fled to Mexico with Mack  and others to try to reconstitute the group there. He was arrested and sent to the United States in March 2018; Mack was arrested a few days later.

"Ms. Mack now understands that this was the best thing that could have happened to her at that time," the defense papers said.

Mack provided information to prosecutors about how Raniere, now 60, encouraged "the use of demeaning and derogatory language, including racial slurs, to humiliate 'slaves,'" the government papers said. More importantly, she provided a recording of a conversation she had with Raniere about the branding, they added.

The branding should involve "a vulnerable position type of a thing" with "hands probably above the head being held, almost like being tied down, like sacrificial, whatever," Raniere told her. The women, he added, "should say, 'Please brand me. It would be an honor.' Or something like that."

Raniere was sentenced last year to 120 years in prison for his conviction on sex-trafficking charges. A 41-year-old heir to the Seagram's fortune, Clare Bronfman, was  sentenced to nearly seven years in prison in September for her role as Raniere's unwavering benefactor.

Mack was allowed to remain out on bail in home confinement until surrendering to prison on Sept. 29. She left the courthouse on Wednesday without speaking to reporters.