Appearing in Brooklyn federal court, Mack pleaded guilty to racketeering and racketeering conspiracy charges related to the suspected sex cult Nxivm.

In a statement, Mack admitted to recruiting women by telling them they were joining a female mentorship group.

"I must take full responsibility for my conduct", she said.

Mack, known for the US television series Smallville, is one of six people facing criminal charges as part of an investigation into Nxivm.

A teary Allison Mack pleaded guilty to two federal counts Monday in the NXIVM sex-cult case.

“I have come to the conclusion that I must take full responsibility for my conduct and that’s why I am pleading guilty today,” said a choked up Mack, who admitted to one count of racketeering conspiracy and one count of racketeering.

Mack attended court in dark relaxed-fit pants and a creamy mock-neck sweater. She kept her hair in a bun and sported leopard sneakers, as she had at her last court proceeding.

Her casual dress stood in stark contrast to the gravity of the situation, as she faces up to 20 years in federal prison on each count.

At the beginning of her allocution, Mack explained in part what drew her to NXIVM. Many of the members were “wonderful people and some of whom, I now realize, were not.”

“I joined NXIVM … to find purpose,” she said of the group, which was headed by co-defendant Keith Raniere. “I truly believed I found a group of individuals who believed as I did.”

“I believed Keith Raniere’s intentions were to help people,” she said. “I was wrong.”

Prosecutors allege that NXIVM, an Albany-area organization that offered costly self-help classes, contained a secretive sect called DOS that “operated with levels of women ‘slaves’ headed by ‘masters.’”

After Mack’s arrest last year, prosecutors said that she served as a “master” under NXIVM founder Keith Raniere, recruited slaves, and “directly or implicitly required her slaves … to engage in sexual activity with Raniere.”

“I was a member of a secret society,” Mack also admitted in court, saying she tried to recruit other women to join DOS.

She said she obtained “collateral” embarrassing information about several women so they would go along with NXIVM’s demands.