The actress' daughter, India, was one of many women coerced into unwanted sex by the group's leader, Keith Raniere.
The accused guru faced charges of racketeering, sex trafficking and child pornography.
The accused cult leader's decision not to call witnesses or testify came after prosecutors finished presenting their evidence over six weeks of trial in Brooklyn federal court.
"Camila" was one of three Mexican sisters who had sex with Raniere, according to prosecutors.
The witness told the court she was blindfolded and strapped to a table while a mystery woman sexually assaulted her under leader Keith Raniere's direction.
Former "slave" Lauren Salzman testified that the accused cult leader hid in a closet from authorities while she tried to protect him from arrest.
A former devotee testified in court that Raniere would make female members paddle each other if they disobeyed him.
A former NXIVM official testified that members believed Keith Raniere was so brilliant the government considered him a threat.
A fellow cult leader read Raniere's words on just how low the age of consent could be in video shown in Brooklyn federal court.
A federal prosecutor told jurors Raniere groomed women for sex, threatening to expose their “deepest, darkest secrets” if they didn’t comply with his wishes.
Trial starts Tuesday in Brooklyn for the alleged cult leader, who has pleaded not guilty to sex trafficking and other charges.
Mack's plea came just hours before jury selection was set to begin in the NXIVM case.
Prosecutors say a secret society within the New York-based self-help group branded women with a leader’s initials.
Clare Bronfman, 39, pleaded not guilty to racketeering charges on Tuesday.
It started in late 2006, when she attended a two-day introduction to Jness in Vancouver.
Mack is not allowed any contact with members of the alleged Nxivm cult.
The actress is accused of recruiting women who were forced to engage in sex with a cult leader.