Allison Mack has pleaded guilty to crimes in connection with the controversial self-help group Nxivm, which prosecutors say sexually exploited women

Smallville star Allison Mack is accused of imposing a restrictive diet on India Oxenberg, the daughter of Dynasty star Catherine Oxenberg and a fellow member of the controversial Nxivm self-help group, to suit the sexual desires of the group’s leader.

The accusation against Mack, who pleaded guilty in April to her role in the a group prosecutors say sexually exploited women, was made by another ex-member during testimony in the sex trafficking and conspiracy trial of group leader Keith Raniere. Raniere has pleaded not guilty.

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The New York Post reports a 31-year-old actress identified only as Nicole testified that Mack, an admitted Nxivm recruiter, put India on a 500-calorie-a-day diet for more than a year, in an effort to get her down to 107 pounds — what she alleged Raniere determined would be India’s perfect weight.

“When India and I became close, they would use her to make me behave,” Nicole explained. “Alison was trying to have [Oxenberg] get down to a certain weight. It was just really hard to watch, sometimes … It was tough on her.”

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The Post reports that previous witnesses have described Raniere’s alleged preference for his “slaves” to be skinny, sleep-deprived and compliant.

Catherine Oxenberg told PEOPLE Mack’s alleged behavior was “horrendous and despicable” and confirmed the reports of her daughter’s restrictive diet.

“I knew India was on a restricted diet of between 500 to 900 calories, but I had no idea it was down to 500 calories for a year,” said Oxenberg. “It’s so many layers of disgust. When you think it can’t get worse, it does. The layers of sadism and cruelty are endless.”

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In 2018, Oxenberg told PEOPLE India had left NXIVM and was “moving forward.”

Prosecutors allege there was a subgroup within Nxivm, known as DOS, which has been described as an all-female secret society in which women allegedly were forced to be sexually subservient to Raniere.

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In April, Mack pleaded guilty to racketeering conspiracy and racketeering. She will be sentenced in September.

Last week, Nicole testified that, when she tried to leave Nxivm, Mack tried luring her back in — and used India to do so.

‘The first thing Allison said is ‘Look what this is doing to India, she hasn’t eaten since she got your email,” Nicole testified of her final meeting with her fellow slaves. “And India said ‘Well, that’s not entirely true.'”

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Oxenberg says India “had no idea she was being starved as a method to control another woman. And so it was startling and horrifying to her.”

PEOPLE was unable to immediately reach Mack for comment.

A second ex-member said Raniere used a spy camera set up in the kitchen of a home he shared with many “slaves.”

“He was surveilling everybody’s food intake,” a Nxivm victim identified only as Daniela told jurors, the Post reports. The woman said Raniere would make a pig noise when women in the group tried to eat.