Representative Nydia M. Velázquez, Democrat of New York, whose district includes the jail, said she was troubled to learn that female inmates might be supervised primarily by men on some nights. “I want to get a commitment that if there are women inmates, that there have to be female officers,” said Ms. Velázquez, who has previously written to the Bureau of Prisons raising concerns about the conditions at the jail.

A spokesman for the Bureau of Prisons, Justin Long, wrote in an email that “the general practice of the Bureau of Prisons is to have at least one male and one female staff on each shift at correctional institutions housing both male and female inmates.”

Sex crimes at the jail are not confined to male correctional officers abusing female inmates: Five years ago, a female correctional officer was impregnated by one of the jail’s most notorious inmates, a man who had been sentenced to death for killing two police officers.

Research has found that nationwide, female employees, while a smaller share of the personnel at correctional institutions, are disproportionately involved in sexual misconduct with inmates.

But the number of sexual assaults reported by the relatively small number of women held at the M.D.C. is striking, pointing to a problem that may be larger than statistics kept by the Bureau of Prisons indicate. In a June report, the Bureau of Prisons stated that in 2016 there were three substantiated cases of “staff-on-inmate” sexual misconduct across its more than 100 jails and prisons. Yet prosecutors from the United States attorney’s office in Brooklyn claim that at least that number of women were sexually abused by staff members in 2016 at the Metropolitan Detention Center alone — a single facility that houses only around 1 percent of the bureau’s inmates.

The warden of the jail, Herman Quay, did not respond to interview requests.

“It raises a lot of questions,” Ms. Velázquez said, referring to the discrepancy in statistics.