A former Columbia University gynecologist who evaded prison time for allegedly sexually abusing dozens of patients was arrested on new federal charges, according to an unsealed indictment in Manhattan federal court.

Robert Hadden, a former Columbia University gynecologist, used his position as a doctor to convince women that repeated sexual abuse was medically necessary, according to prosecutors with the U.S. Southern District of New York. The alleged abuse occurred between 1993 and 2012 at the university hospital, which is not specifically named in the indictment.

Among the six unnamed victims in the indictment was a minor, who Hadden himself had delivered as a baby, the indictment says.

"Hadden allegedly used the examinations of his victims for his own sexual gratification, abusing dozens of victims over a nearly 20-year period, including multiple minor girls, one of whom Hadden had himself delivered," Acting U.S. Attorney Audrey Strauss said in a statement.

Federal prosecutors allege Hadden would repeatedly touch his victims' genitals and breasts for non-medical purposes while alone in the room with them—including licking their genitals. According to the indictment, Hadden would bring up sexual topics and ask "detailed, inappropriate questions" about his patients' sexual partners and activity. During the conversations, he would make comments about their appearance or offer unsolicited advice on grooming.

"The allegations show that Hadden acted as a predator in a white coat," Strauss said.

Federal authorities arrested 62-year-old Hadden in Englewood, New Jersey.

The charges come months after Manhattan District Attorney Cy Vance opened a new investigation into Hadden after a public outcry sparked by Hadden's no-prison plea deal with Vance's office.

All twelve members of the City Council's women's caucus, the public advocate, and two former patients have demanded Vance resign because of his handling of the Hadden case, and other high profile cases against powerful men, like convicted rapist Harvey Weinstein. In January, Evelyn Yang, former cosmetics executive and also the wife of former presidential candidate Andrew Yang, came forward to reveal that Hadden had sexually assaulted her while she was pregnant.

"I stand in solidarity with the countless women who stepped forward to share their truth about our abuser," said Marissa Hoechstetter, an activist who is fighting to reform the Manhattan DA's Sex Crimes Unit who has also accused Hadden of sexually abusing her, but is not among survivors in this indictment. "I hope that through the course of this, the world will finally see the full extent of Hadden's decades of sexual abuse and the institutional cowardice that protected and enabled him for so long."

She added in a statement: "At a time when the world is focused on criminal justice reforms and the power of district attorneys, the Hadden story is a shining example of our flawed two-tiered system of justice. This federal indictment only puts into high relief the betrayal I and his other victims experienced by the Manhattan DA."

A spokesperson for the district attorney, Danny Frost, said Vance's office had "provided substantial assistance" leading to the indictment.

Vance's investigation examining "potential failures by Dr. Hadden's employer and hospital to disclose additional incidents of abuse to our office and to regulators when required" is "intensely active and ongoing," Frost added.

A spokesperson for Columbia University said in a statement: "Nothing is more important to Columbia than the safety of our patients, and we condemn sexual misconduct in any form."

"We commend the women who have spoken out against Robert Hadden and will cooperate fully with the U.S. Attorney's Office as the case against him proceeds," the university spokesperson added.

Hadden, who hasn't worked at the university since 2012, faces six counts of "enticing and inducing individuals to travel interstate to engage in illegal sexual activity." Each count carries a maximum 20-year prison sentence.

A lawyer for Hadden, Isabelle Kirshner, declined to comment, but added that Hadden planned to plead not guilty.