Prosecutors accused Mack, who had a starring role in the TV hit Smallville, of helping Raniere recruit women to a secret sub-society within the group. Until the Salzmans' guilty pleas, officials and associates had repeatedly denied all wrongdoing and disputed allegations that it is a cult. Mack pleaded guilty to racketeering charges on Monday in a case involving a cult-like group based in upstate NY.
The women in DOS were also allegedly branded in the pubic region during super-secretive ceremonies with a symbol that later appeared to be Raniere's initials.
In earlier submissions to the court, she admitted to being part of DOS, but contended in court documents that no one's collateral was ever released, that she never received any money from her participation in the group and that she "never instructed anyone to partake in a sex act, and did not even know that the alleged sex acts were occurring".
"I believed Keith Raniere's intentions were to help people, and I was wrong", she told a judge in federal court in Brooklyn, New York City, as she pleaded guilty to racketeering.
Mack, 36, wept as she admitted her crimes and apologised to the women who prosecutors say were exploited by Keith Raniere and the purported self-help group called NXIVM, based in upstate ny.
Mack played Chloe Sullivan, a close friend of the future Superman whose crush on him was unrequited.
The guilty plea means Mack will avoid going to trial with Raniere and two women in NXIVM's inner circle, Clare Bronfman and Kathy Russell. Defense attorneys have insisted any relationship between Raniere and the alleged victims, including an unidentified actress and other women expected to testify against him at trial, was consensual.
Mack is facing up to 20 years in prison.
Raniere, Mack, and four others were arrested past year for the involvement with NXIVM, a Colonie, N.Y. -based group that claimed to be a self-help organization.