NEW YORK (CBSNewYork/AP) – A former TV actress who became involved with NXIVM, an alleged self-help group turned New York-based sex cult, entered a guilty plea in a Brooklyn courtroom today.

Allison Mack was best known for her role as a young Superman’s close friend on the TV series “Smallville.”

Mack pleaded guilty to two counts, racketeering conspiracy and racketeering. Her sentencing is set for Sept. 11.

READ: Superseding Indictment Vs. Keith Raniere aka “Vangard,” “Grandmaster” and “Master”, Clare Bronfman, Allison Mack, Kathy Russell and Lauren Salzman

Earlier on Monday, potential jurors were summoned to federal court to fill out questionnaires in the sex-trafficking case against Keith Raniere and co-defendants prosecutors say were part of an inner circle of enablers.

WATCH: Exclusive: Woman Says ‘Smallville’ Star Allison Mack Propositioned Her To Join Women’s Empowerment Group

Also accused is heiress Clare Bronfman, a daughter of the late billionaire philanthropist and former Seagram chairman Edgar Bronfman Sr., and actress.

Two other women charged in the case, former NXIVM executive Nancy Salzman and her daughter, Lauren, have already pleaded guilty.

Lauren Salzman entered her plea at a hearing that did not appear on any public calendar, and prosecutors had portions of a transcript blacked out. That’s led to speculation she may cooperate against alleged cult members at trial.

READ: Civil Complaint To Seize Properties In Halfmoon, N.Y.

Actress Allison Mack arrives at the United States Eastern District Court for a bail hearing in relation to the sex trafficking charges filed against her on May 4, 2018, in Brooklyn. (credit: Jemal Countess/Getty Images)

Salzman admitted holding a women from Mexico hostage in an upstate home for more than two years under threat of having her deported “if she did not complete labor requested by myself and others,” according to the redacted transcript.

The jury questionnaire covers several topics, including asking candidates for their opinions about “rich individuals,” about people who “engage in relationships with multiple sexual partners” and whether they “believe that people under the age of 17 should be able to consent to sex with adults.”

READ: Civil Complaint To Seize Properties In Halfmoon, N.Y.

Previously, the civil complaint document gave some insight into other rituals and practices of the NXIVM group, which authorities say grew out of a previous enterprise called Executive Success Programs, Inc. (“ESP”) founded in 1998 by Raniere and Nancy Salzman.

Keith Raniere

“Every year in August, Nxians celebrate ‘Vanguard Week’ in honor of Raniere’s birthday,” the complaint said. “Nancy Salzman is referred to as ‘The Prefect’; by Nxians, and her birthday is celebrated in May with the ‘Festival of Flowers.'”

The complaint also described women’s roles in the empowerment group compared to the men, and especially Raniere as its leader.

NXIVM was the topic of a CBC News podcast “Uncover: Escaping NXIVM” focusing on Canadian actress Sarah Edmondson’s experience with and leaving the group.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)