Washington, D.C. Mayor Muriel Bowser announced Monday an internal investigation after deputy mayor and longtime adviser John Falcicchio's unexplained departure last week. 

 "As you are aware, last week John Falcicchio departed from the DC government. I know you have many questions, but please understand that as this is a sensitive matter that includes privacy concerns, we will not be able to discuss it any further," Bowser said. "However, I am able to say that the circumstances of his departure led me to initiate an investigation.

"The legal counsel’s office is leading the investigation, following established policies and procedures. I have made it clear that my expectation is that all staff will cooperate fully with this investigation," she added.  "I can also tell you that this investigation does not involve any allegations of improprieties related to business transactions.

"There is no reason for our important work on behalf of the residents of the District of Columbia to slow down. I have every confidence in my new Chief of Staff, Lindsey Parker, and in our Interim Deputy Mayor, Keith Anderson, and in the 37,000 employees of DC Government to keep us moving ahead," Bowser said in a statement. 

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Bowser and Bowser and John Falcicchio wearing I stand with Black women t-shirt

DC Mayor Muriel Bowser announced a probe into former Deputy Mayor John Falcicchio aft his unexplained departure from her administration last week. (Marvin Joseph/The Washington Post via Getty Images)

Falcicchio, whose Twitter bio now describes him as an "alum" of Bowser's administration, left his role as Chief of Staff and Deputy Mayor of Planning and Economic Development. He did not provide an explanation. At a press conference Monday, Bowser declined to go into any detail about the investigation, deferring most questions Vanessa Natale, the deputy director of the Mayor's Office of Legal Counsel (MOLC). MOLC Director Eugene Adams is leading the investigation. 

Bowser and John Falcicchio walk down hallway in 2015

Mayor Muriel Bowser, seen accompanied by John Falcicchio in 2015 following her election to office, announced an investigation into her former adviser.  (Marvin Joseph/The Washington Post via Getty Images)

"The scope of the investigation is based upon the sensitive matter. I will tell you — it's not jargon — but there are privacy concerns," Natale said. "As in any investigation our office undertakes, we follow our standard policies and procedures which include confidentiality and the integrity of the witnesses and anyone who can come forward and speak.  

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"This is a sensitive matter with privacy concerns, and, therefore, will not be made public," Natale said. "As with any investigation, criminal behavior would be referred to our Office of the Inspector General, MPD, USAO, whoever would be - ya know – involved in that."  

Bowser stands at podium

DC Mayor Muriel Bowser declined to go into detail on the John Falcicchio probe, citing privacy concerns regarding the "sensitive matter." (AP Photo/Andrew Harnik, File)

In a news release Friday, Bowser's administration thanked, "Deputy Mayor John Falcicchio for his years of service to the District as he transitions to the private sector," offering no other reasoning. Bowser said Monday no other employees were removed, suspended or stepped down from their posts as a result of the investigation. 

Falcicchio's departure comes months after Chris Geldart, the former Deputy Mayor for Public Safety and Justice, resigned from Bowser's administration amid assault charges. 

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Those charges were later dropped. Video of an alleged parking lot confrontation between Geldart and a personal trainer in nearby Virginia circulated online, but the Arlington County Commonwealth’s Attorney later said it was unclear who was the aggressor in that incident.