TV actress Allison Mack pleaded guilty Monday to charges she was involved in a scheme to turn women into sex slaves for the spiritual leader of a cult-like upstate New York group, a development that came on the same day jury selection began for a federal trial in the case.

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.

“I believed Keith Raniere’s intentions were to help people, and I was wrong,” Mack told a Brooklyn judge.

Mack - best known for her role as a young Superman’s close friend on the series Smallville - said that after months of reflection since her arrest, “I know I can and will be a better person.”

The actress is to be sentenced Sept. 11 on two racketeering counts that each carry maximum terms of 20 years in prison. However, it’s likely she would face far less time under sentencing guidelines.

The plea means Mack will avoid going to trial with Raniere, wealthy heiress Clare Bronfman and another member of Raniere’s inner circle, Kathy Russell. All have pleaded not guilty and denied any wrongdoing.

Court papers allege NXIVM formed a secret society of women who were branded with Raniere’s initials and forced to have sex with him. 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.

On Monday, Mack said that at Raniere’s direction, she obtained compromising information and images of two unidentified women - called “collateral” within the group - that she threatened to make public if they didn’t perform “so-called acts of love.”

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