A Michigan-based doctor and her associates mutilated the genitals of as many as 100 girls before being caught, a prosecutor told a federal court Wednesday.

The startling allegation occurred during court proceedings involving a case against Dr. Jumana Nagarwala, who is facing charges for mutilating the genitals of two Minnesota girls. (Maine ACLU: Female Genital Mutilation Should Not Be A Crime)

“Due to the secretive nature of this procedure, we are unlikely to ever know how many children were cut by Dr. (Jumana) Nagarwala,” said U.S. Attorney Sara Woodward, accordingto the Detroit Free Press. “The Minnesota victims were not the first victims.”

Nagarwala is alleged to have cut the genitals of the girls as part of a religious rite of passage. The two girls are believed to have been told to keep the practice a secret. (Michigan Doc Charged With Female Genital Mutilation Of 6-Year-Old Girls)

U.S. District Judge Bernard Friedman granted bond to Dr. Fakhruddin Attar and his wife, Farida Attar. Dr. Attar is accused of allowing Nagarwala to use his clinic, located just outside Detroit, to engage in the mutilations, while his wife allegedly held the girls’ hands down during the procedure.

The group’s activities were discovered by an FBI investigation, which led to the Justice Department filing charges against them in April.

Girls as young as six years old were involved in the secretive operations, according to an FBI criminal complaint.

The prosecution claimed that the three defendants engaged in the mutilations over a 12 year period. All are part of the same Indian-Muslim sect, known as the Dawoodi Bohra. Some cultures consider female genital mutilation to be a “necessary part of raising a girl, and a way to prepare for adulthood and marriage,” accordingto the World Health Organization.

Mary Chartier, a lawyer for the Attars, denied any criminal activity, and argued the practice is protected as a religious act that involves no cutting, only scraping of the girls’ genitals. (Two More Muslims Arrested For Female Genital Mutilation At Detroit-Area Clinic)

“I think the government has overstated so many aspects of this case, and this is one more example of overreaching,” said Chartier after the hearing.

The Attars will be forced to surrender their passports and will be put under house arrest with GPS monitors. They will only be allowed to leave home for approved visits to doctors and their lawyers. Nagarwala remains in custody.

Nagarwala and Dr. Attar could face life in prison, if convicted, while Mrs. Attar could be given up to 20 years. Trial is set for October 10.