It's no secret that Mayor Bill de Blasio long ago soured on Mark Peters. He was once his campaign treasurer. As the commissioner of the city's department of investigation (DOI), Peters has uncovered significant wrongs in de Blasio's administration, like lead paint in public housing, parking placard abuse, and proof that the former city correction commissioner was driving his official car to his home in Maine. That led the commissioner to resign.

All the while, to some, Peters overstepped his boundaries in trying to take control of the office overseeing public schools.

Last November, de Blasio pointedly wasn't willing to defend him: "I'm not going to speak about any personnel matters," the mayor said.

Reportedly, City Hall has been eyeing firing Peters. The Daily News has reported that de Blasio administration officials wrote a seven-page dossier explaining Peters should be gone "because he has taken actions that exceed his lawful authority and has engaged in threatening, coercive and abusive behavior and otherwise conducted himself in a manner that is unbecoming of a public servant," officials reportedly wrote in the dossier.

De Blasio never signed the dossier, and City Hall declined to answer questions about it Friday.

According to the Daily News, the dossier finds Peters "used abusive language or threatened to arrest city employees if they didn't do what he wanted."

It reportedly surrounds his bid to find new agency headquarters, with a new lease for it attracting concern from City Comptroller Scott Stringer and defense from the Department of Citywide Administrative Services.

Under city law, the mayor needs a reason to axe the commissioner, who is a watchdog over the administration.

Peters told the Daily News he disputes how he was portrayed in the document. He also declined to comment to NY1.

Bronx City Councilman Ritchie Torres, who chairs the Committee on Oversight and Investigation, called the dossier troubling but noted the mayor never signed it.

"So it's a hypothetical," Torres said. "It creates the impression that the administration is conspiring to undercut the independence of DOI and to undercut the DOI commissioner."

The office began in 1873 to target municipal corruption. At least in modern New York history, there's no record any mayor firing a sitting department of investigation commissioner