The investigator leading the probe into the Secret Service's 2012 prostitution scandal quietly resigned in August after he was implicated in a prostitution entanglement of his own.

A senior administration official confirmed to Fox News that David Nieland was observed entering and leaving a building that was under surveillance as part of a prostitution investigation by sheriff's deputies in Broward County, Fla.

Authorities later interviewed a prostitute who identified Nieland in a photo and said he had paid her for sex.

Nieland resigned after he refused to answer questions from a Department of Homeland Security official about the incident. The circumstances behind Nieland stepping down were first reported by The New York Times.

A spokesman for the DHS's inspector general told the Times he could confirm only that Nieland resigned in August. But he said department officials became aware in early May of "an incident in Florida that involved one of our employees."

Nieland, the former head of the inspector general's Miami office, said "the allegation is not true" and declined to answer any questions from the paper.

Nearly two dozen Secret Service agents were disciplined or fired as part of the scandal, which began when Secret Service agents brought prostitutes into their hotel in Cartagena, Colombia ahead of President Obama's trip to the Summit of the Americas in April 2012.

Earlier this month, The Washington Post reported that Nieland told Senate aides conducting their own investigation into the scandal that he was instructed to delay his report until after the 2012 presidential election.

The Post reported that Nieland said that he was instructed by his superiors in the DHS inspector general's office to "withhold and alter certain information in the report of investigation because it was potentially embarrassing to the administration." The information in question involved claims that a member of the White House advance team was also involved in the prostitution scandal. Both the White House and the former advance team member, Jonathan Dach, have denied any wrongdoing on his part.

Charles Edwards, the Department of Homeland Security's acting inspector general at the time of the investigation, told the Senate staffers that any changes to the report were part of the editing process. Nieland and two other members of the office later claimed that they were put on administrative leave for questioning the changes to the report, claims that The Post reports their superiors denied.

Fox News' Jennifer Griffin contributed to this report.