Nxivm is based out of Albany, New York, and has been the subject of scrutiny from both law enforcement and journalists after it came under fire from Dynasty actress Catherine Oxenberg, whose estranged daughter, India, joined the group in 2011.
In March, the group’s founder, Keith Raniere, was arrested on federal charges of sex trafficking, sex trafficking conspiracy and forced labor conspiracy.
Last Friday, Mack, 35, was arrested on the same charges.
Here are seven things to know about the case.
1. Mack Is Best Known for Playing Wholesome Chloe Sullivan on The WB’s Smallville
Before her arrest, Mack had an extensive list of acting credits. As a child actress, she had roles in several TV movies and guest starred on shows such as Providence, Empty Nest, Evening Shade and 7th Heaven. In 2001, she landed the role of Chloe Sullivan on the WB’s Smallville — a role she played for 10 years.
After Smallville ended in 2011, Mack continued to act and do voiceover work. In recent years, she appeared in FX’s Wilfred and on The Following, on Fox, among other periodic TV roles.
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2. Mack Allegedly Recruited Women to Be Sex ‘Slaves’
According to a statement from prosecutors after Mack’s arrest, the actress allegedly recruited women to join what was purported to be a female mentorship group to address their weaknesses but was actually a group created by Raniere that allegedly took advantage of women sexually.
“The victims were then exploited, both sexually and for their labor, to the defendants’ benefit,” Richard P. Donoghue, U.S. Attorney for the Eastern District of New York, said in the statement.
Prosecutors allege Raniere ran Nxivm like a “pyramid scheme” and created a secret society within the group called “DOS” — which according to prosecutors is “an acronym standing for a Latin phrase that loosely translates to ‘Lord/Master of the Obedient Female Companions.’ ”
Investigators allege Raniere, who was known as “Vanguard” within the group, occupied the top of the pyramid and was the DOS’s only male member. Beneath him were tiers of female “slaves,” each of whom could become a “master” by recruiting other women into the group, according to prosecutors.
Mack and other women occupied the next tier down from Raniere, authorities believe. According to a letter prosecutors sent to the judge opposing Mack’s bail, the actress “was focused on recruiting attractive young women who could meet Raniere’s sexual preferences.”
3. The Female ‘Slaves’ Were Allegedly Blackmailed and Branded With Raniere’s Initials
Authorities allege 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.
Prosecutors allege that the women Mack is accused of victimizing, referred to in the indictment as Jane Doe 1 and Jane Doe 2, “believed that if they did not participate in [sexual] activities with Raniere, their collateral would be released.”
Authorities suspect Mack forced DOS slaves, including Jane Doe 1, to have sex with Raniere and that Mack “groomed DOS slaves for sex with Raniere by requiring [them] to adhere to extremely restrictive diets and not remove their public hair (in accordance with Raniere’s sexual preferences) and by requiring them to remain celibate and not to masturbate.”
According to arguments prosecutors made in court documents, Mack allegedly demanded that the group’s slaves partake in “readiness” drills requiring them to respond to their masters at any time of night.
Mack’s slaves were “kept seriously sleep-deprived and emaciated to the point where they stopped menstruating,” prosecutors allege.
Additionally, DOS slaves were allegedly “branded in their pelvic regions with a cauterizing pen with a symbol that, unbeknownst to them, incorporated Raniere’s initials.”
4. During Brandings, Mack Allegedly Told ‘Slaves’ to ‘Think Of [Their] Master’
Prosecutors claim that during ceremonies in which her slaves were branded, Mack “placed her hands on the slaves’ chests and told them to ‘feel the pain’ and to ‘think of [their] master,]’ as the slaves cried with pain.”
The prosecutor’s letter to the judge in Mack’s case also alleges that she “provided naked photographs of her slaves to Raniere and was aware of Raniere’s proclivity for having sex with multiple young women.”
In return, according to the letter, Mack allegedly “received financial benefits of the form of continued status and participation in DOS, as well as financial opportunities from Raniere.”
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. (It was taken offline after her arrest.)
5. Mack and Raniere Face at Least 15 Years in Prison
Both Mack and Raniere face a minimum sentence of 15 years in prison if convicted on all of their charges.
Raniere has not yet been arraigned or entered a plea. Mack pleaded not guilty to the charges Friday.
Attorneys for Mack and Raniere have not returned PEOPLE’s numerous requests for comment.
Mack appears to be trying to negotiate a plea agreement. Federal prosecutors disclosed their pending plea negotiations in a joint petition filed Friday, which the judge approved.
The application, obtained by PEOPLE, shows both parties sought the exclusion “because they are engaged in plea negotiations, which they believe are likely to result in a disposition of this case without trial.”
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.”
6. Mack Reached Out to Emma Watson About Group
In tweets written to the Harry Potter actress in 2016 and unearthed by Business Insider, Mack reached out to Emma Watson, 28, about an “amazing women’s movement” she wanted to speak to the actress about, although she never mentioned Nxivm by name in her tweets.
“.@EmWatson I’m a fellow actress like yourself & involved in an amazing women’s movement I think you’d dig. I’d love to chat if you’re open,” Mack, 35, tweeted.
.@EmWatson I'm a fellow actress like yourself & involved in an amazing women's movement I think you'd dig. I'd love to chat if you're open.— Allison Mack (@allisonmack) January 24, 2016
One month later, in February 2016, Mack tweeted at Watson again, writing, “.@EmWatson I participate in a unique human development & women’s movement I’d love to tell you about. As a fellow actress I can relate so well to your vision and what you want to see in the world. I think we could work together. Let me know if you’re willing to chat.”
7. She Bonded Out of Jail and Will Stay With Her Parents in California
On Tuesday, Mack was released from jail but will remain under house arrest at her parents’ home in California, where she will be monitored electronically.
She will also be barred from associating with any former or current members of Nxivm.
She was escorted away from a Brooklyn, New York, federal court on Tuesday after posting a $5 million bond.