Smallville Actress Allison Mack Is Negotiating a Possible Plea After Sex Trafficking Arrest

Actress Allison Mack is working out a possible plea following her Friday arrest on sex trafficking charges in connection with Nxivm — a controversial self-help group described by one former member as a “cult” — PEOPLE learns.

Mack, 35, and federal prosecutors disclosed their pending plea negotiations in a joint petition filed Friday, asking the court to exclude the next several days from the larger period of time under which Mack’s speedy trial must begin.

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.”

The prosecution and defense “require an exclusion of time in order to focus efforts on plea negotiations without the risk that they would not, despite their diligence, have reasonable time for effective preparation for trial,” the petition continues.

The judge in Mack’s case approved their request, court records show. She was scheduled to return to court for a detention hearing on Monday.

Mack faces three federal charges in connection with Nxivm, whose co-founder Keith Raniere was arrested in Mexico in March on the same three accusations. Both are accused of sex trafficking, sex trafficking conspiracy and forced labor conspiracy for their alleged roles in running a secretive sub-group within Nxivm involving “masters” and “slaves.”

The former Smallville costar faces at least 15 years in prison if convicted on all of her charges. She reportedly pleaded not guilty during her first court appearance in the case, in New York City, on Friday.

Mack — who appeared in FX’s Wilfred and The Following, on Fox, after Smallville ended — 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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A representative for Mack has declined to comment to PEOPLE on her arrest. Attempts to contact her attorney, Sean Stephen Buckley, have not been returned.

Raniere’s lawyer could not immediately be reached by PEOPLE. He has yet to be arraigned.

Nxivm, formed around 2003 and based out of Albany, New York, has been the subject of scrutiny from both law enforcement and journalists as it came under fire from Dynasty actress Catherine Oxenberg, whose estranged daughter, India, joined the group in 2011.

“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, 56, told PEOPLE after Mack was arrested.

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.

Nxivm has not responded to numerous requests for comment from PEOPLE but 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.”

In the fall, the group denounced a New York Times article about them as “a criminal product of criminal minds.”

• With reporting by STEVE HELLING