In February, a federal judge denied a third request for bail from Raniere, meaning he will remain behind bars until at least April 29 - the scheduled start of his trial on sex trafficking and forced labor charges.
Jury selection is set to begin for a trial featuring sensational allegations that a cult-like group based in upstate NY turned women into sex slaves who were branded with the initials of its spiritual leader.
John Marzulli, Public Information Officer for the U.S. Attorney's Office for the Eastern District of NY confirmed Mack's plea, which was entered Monday.
"Smallville" actress Allison Mack on Monday pleaded guilty to blackmailing two women as part of an alleged NY sex cult that prosecutors called a racketeering operation that carried out sex trafficking and other crimes.
Mack had been charged alongside NXIVM founder Keith Raniere, with whom she allegedly recruited and groomed slaves under the guise of building a self-help, female-empowerment organization.
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After months of reflection since her arrest, "I know I can and will be a better person", Mack said.
The women were allegedly forced to perform services under the threat of serious harm, adhere to strict diets of only 900 calories a day, and endure a ceremony in which Raniere's initials were branded into their skin with a hot cauterizing pen. Variety reported that Mack was previously in negotiations for a plea deal with authorities. If convicted of those charges, she would have faced life in prison.
Last month, prosecutors unsealed new charges accusing Raniere of sexually exploiting a minor and coercing her to produce child pornography. She pleaded not guilty at the time.
Raniere was arrested on sex trafficking charges in March past year and is being held without bail.
Clare Bronfman leaves Brooklyn federal court in NY on July 25, 2018.
Others facing charges include NXIVM bookkeeper Kathy Russell and wealthy Seagram's liquor heiress Clare Bronfman. NXIVM president Nancy Salzman and her daughter, Lauren, entered guilty pleas that were partly redacted, suggesting they may be cooperating against the other defendants in the trial to receive a reduced sentence.