Mayor Muriel Bowser on Monday said she had launched an investigation into accusations of sexual harassment that prompted her longtime confidante and deputy mayor John Falcicchio to resign suddenly from the D.C. government last week.

Speaking at a press conference, Bowser declined to detail what specific allegations had prompted Falcicchio’s departure, other than to say they did not involve any “improprieties related to business transactions.” But within hours of her announcement, attorneys Debra S. Katz and Kayla Morin said the investigation stemmed from allegations of sexual harassment — including unwanted advances and sexual contact — from a D.C. government employee.

“We represent an employee of the District of Columbia who came forward to report serious allegations of sexual harassment by former Chief of Staff and Deputy Mayor for Planning and Economic Development John Falcicchio. It is our understanding that this behavior is longstanding and our client is cooperating fully with the investigation, which Mayor Bowser initiated immediately. Our client is courageous. She came forward to ensure accountability and protect other women,” the pair said in a statement.

Bowser’s investigation and the attorneys’ statement came as rumors circulated wildly over the weekend over what led to Falcicchio’s sudden departure from her administration. This comes after more than eight years of loyal service to the mayor, and a political proximity to her that gave him huge amounts of power and influence. Falcicchio served not just as Bowser’s key campaign pitchman during her three runs for the city’s top office, but also as her chief of staff for the last eight years and also as her deputy mayor for planning and economic development for the last four.

Falcicchio was strangely absent from a marquee economic development event last Thursday, with his exit from government service only briefly mentioned at the bottom of a press release the following afternoon, in which he was tersely thanked for his service “as he transitions to the private sector.” He has not responded to press requests for comment since then, and Bowser’s aides have remained tight-lipped about what exactly had happened.

While Bowser said an investigation would help address allegations floating around Falcicchio in the lead-up to his departure, she said the outcome may never be disclosed to the public. “This is a sensitive matter that includes privacy concerns,” she said.

Katz and Morin, known for representing other high-profile victims of sexual harassment, asked for their client’s privacy to be respected, but also requested that any other potential victims contact the Mayor’s Office of Legal Counsel, which is leading the investigation.

The only thing Bowser would confirm is that the allegations that led to Falcicchio’s departure did not have anything to do with rumored accusations of misbehavior on a four-day, five-city bus tour sponsored by the city’s government to promote tourism ahead of the National Cherry Blossom Festival. But multiple sources who contacted DCist/WAMU over the weekend said rumors of Falcicchio’s misconduct were widespread.

“He was a ‘Me Too’ waiting to happen,” said one, citing the survivor-led global movement against sexual harassment and violence.

The accusations that prompted Falcicchio’s departure represent an unwanted scandal in the early months of Bowser’s third term, one involving one of her closest aides who also managed one of the government’s most significant portfolios. Falcicchio was a central figure in Bowser’s Comeback Plan for downtown D.C., which foresees turning the area into a livelier and livable destination.

“What people want to know is that we’re moving forward on the very important work that ahead, and the comeback of our downtown is among our most important [projects],” Bowser said Monday.

Last week Bowser appointed Keith Anderson, who currently serves as the director of the D.C. Department of General Services, to be interim deputy mayor for planning and economic development, and Lindsay Parker, the current assistant city administrator, to serve as chief of staff.

Falcicchio’s departure follows similar exits by other senior aides, including Chris Geldart, Bowser’s longtime deputy mayor for public safety and justice, who resigned late last year after he was charged with assault and found to be residing in Virginia, violating a city requirement that he live in D.C.