Oxenberg is speaking out about the recent arrest of the Smallville actress in connection with the controversial self-help group and alleged "cult" Nxivm

Actress Catherine Oxenberg is speaking out about the recent sex-trafficking arrest of Smallville‘s Allison Mack in connection with controversial self-help group Nxivm — described by one former member as a “cult” — where Mack is suspected of operating as a key lieutenant.

The group, based in Albany, New York, has counted Oxenberg’s estranged daughter, India, among its members since 2011.

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“I hope the arrest of Ms. Mack will continue to expose what Nxivm is — a dangerous cult — and the members, including my daughter, will come to that realization and find their way back to their loved ones,” Oxenberg tells PEOPLE exclusively.

The group’s co-founder Keith Raniere was arrested in Mexico in March on federal charges of sex trafficking, sex trafficking conspiracy and forced labor conspiracy.

Mack, 35 — best known for her years-long role as Chloe Sullivan on The WB’s superhero series — was taken into custody earlier this month and faces the same charges as Raniere. She has reportedly pleaded not guilty and is set to appear in court again on Monday; Raniere has not yet pleaded or been arraigned.

A representative for Mack declined comment to PEOPLE on her arrest. It was unclear if Mack or Raniere have retained attorneys who could speak on their behalf.

Mack has previously discussed her connection with Raniere. “Over the course of several years, Mr. Raniere mentored Allison in her study of acting and music,” her website stated until her arrest (after which it was taken offline).

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Image zoom Allison Mack Matt Baron/BEI/REX/Shutterstock

Image zoom Catherine Oxenberg Allison Michael Orenstein

The Case So Far

Formed around 2003, Nxivm has recently been the subject of scrutiny from both law enforcement and journalists as it came under fire from Oxenberg, 56.

The actress, who played Amanda Carrington on Dynasty in the mid-’80s, first opened up to PEOPLE last year about how she believed India had been “brainwashed” by Nxivm.

In the fall, India posted on Facebook that she was “absolutely fine, great actually [and] I would never put myself or the people I love into any danger.”

For the past two decades, an estimated 16,000 people have paid as much as $3,400 for an executive coaching workshop offered by Nxivm, which promises to take participants on a journey of personal discovery and development, according to previous PEOPLE reports.

The criminal complaint against Raniere — known as “Vanguard” to his followers — alleged that he encouraged the formation of a secretive subgroup within Nxivm called “Dominus Obsequious Sororium,” (DOS) in which women were coerced into serving as sex slaves to their male masters.

The complaint, which was obtained by PEOPLE, outlines how authorities believe the women were forced to turn over “collateral” — identified as potentially-damaging personal information or materials, such as nude photographs — with which they later could be blackmailed.

The complaint against Raniere additionally alleges the women were branded with his initials, as he “alone forms the top of the pyramid as the highest master.” A cauterizing pen was used to make the permanent marks near each person’s pubic region, the complaint claims.

Image zoom Keith Raniere

Image zoom Allison Mack (left) in Smallville Everett

According to a statement on Friday from federal authorities, Mack is accused of recruiting women to join DOS purportedly because it was a female mentorship group to address their weaknesses but was actually a group created by Raniere that allegedly took advantage of women.

“The victims were then exploited, both sexually and for their labor, to the defendants’ benefit,” said Richard P. Donoghue, U.S. Attorney for the Eastern District of New York.

FBI Assistant Director-in-Charge Sweeney said in the statement that the case has “brought to light an inconceivable crime,” referring to NXIVM as a “pyramid scheme” at which Raniere stood alone at the top, with a level of female “slaves” underneath.

According to the statement, Mack was allegedly “one of the women in the first level of the pyramid immediately below Raniere.”

As such, she allegedly had “slaves” underneath her, according to the statement, which claims Mack “directly or implicitly required” two women “to engage in sexual activity with Raniere.”

“In exchange, for this, Mack received financial and other benefits from Raniere,” the statement alleges.

The women victimized by Mack believed their “collateral” would be released if they did not engage in sexual activity with Raniere, the statement on Mack’s arrest alleges.

Both Mack and Raniere face a minimum sentence of 15 years in prison if convicted on all of their charges.

Nxivm, which has not responded to numerous requests for comment from PEOPLE, issued a statement in support of Raniere soon after his arrest, writing in part: “We are currently working with the authorities to demonstrate his innocence and true character.”