NEW YORK (CBSNewYork) — Federal investigators questioned Mayor Bill de Blasio for nearly five hours Friday about a corruption probe that has been swirling around City Hall for nearly a year.

As CBS2 Political Reporter Marcia Kramer reported, de Blasio’s political future hung in balance Friday. But after his faceoff with the feds, the mayor had absolutely nothing to say – and he used police officers to help shield him.

As de Blasio was about to end his highly-anticipated session with prosecutors and FBI agents, he had his police detail put up barricades – and then station a phalanx of detectives and officers to keep reporters at bay.

Kramer asked de Blasio: “Mr. Mayor, how did it go? What did you tell the prosecutors?” One officer tried to physically restrain her from following the car as she pointed out that she is allowed to walk on a public street.

But that did not stop CBS2 cameramen from capturing the mayor in the back seat of his sport-utility vehicle doing his best to ignore the demands for answers.

It added to the drama and the spectre of the Mayor of the City of New York being forced to defend his actions as part of a corruption probe.

Despite his reputation for tardiness, de Blasio arrived 20 minutes early Friday for his 9:30 a.m. date with prosecutors and FBI agents investigating whether the mayor or his aides gave donors favorable treatment in exchange for campaign cash, Kramer reported.

He spent the prior two days preparing his testimony.

The @NYCMayor has left the building -after nearly 5 hrs of ques by Feds #video#1010wins pic.twitter.com/B7NcXSxAEr — Juliet Papa (@winsjuliet) February 24, 2017

De Blasio has repeatedly denied any wrongdoing, saying everything was done with the advice of his legal team.

His office released a statement saying the mayor voluntarily met with investigators.

“We remain confident that at all times the mayor and his staff acted appropriately and well within the law,” City Hall Press Secretary Eric Phillips said. “We hope our continued cooperation will help bring a swift conclusion to the U.S. Attorney’s review. In the interest of protecting the integrity of this process, we will refrain from any further comment at this time.”

The mayor left Gracie Mansion in his SUV at 8:45 a.m. Mobile 2 followed the two-car caravan as it made it’s way down the FDR Drive, then across town to the office of his attorney near Rockefeller Center. The security car in the rear finally put on its lights and blocked Mobile 2 just before it’s arrival so de Blasio could not be seen going into the building, Kramer reported.

The mayor never rolled down his window as he arrived for the meeting and the army of detectives and security were on hand to keep reporters at bay from the beginning, Kramer reported. Prosecutors also declined comment.

The investigation centers around accusations that the mayor and his aides gave favorable treatment to donors who contributed to the mayor’s 2013 election campaign.

For nearly a year, U.S. Attorney Preet Bharara has probed donations to the campaign and the mayor’s now-defunct political action committee. Sources say the feds want to question the mayor about a dozen topics including contributions by Harendra Singh, who is negotiating a lease for the Water’s Edge restaurant in Long Island City, property owned by the city.

Singh, who was arrested on unrelated bribery and fraud charges is cooperating with prosecutors. He also cooperated in the investigation that lead to the indictment of Nassau County Executive Ed Mangano.

It’s not clear whether the investigation is focused on the mayor himself or others within his administration.

The mayor spoke to investigators without immunity — no deal — but sources said with no plans to go before a grand jury, 1010 WINS’ Juliet Papa reported.

The interview was apparently supposed to take place two weeks ago, but was postponed.

Gerald Lefcourt, one of the city’s top defense attorneys, earlier this month explained to Kramer how important Friday was for the mayor.

“This is the biggest moment in his life,” Lefcourt said. “Certainly he has to be very careful because everything is on the line.”

Last December, de Blasio was fined nearly $48,000 for violating spending rules during his 2013 campaign for mayor.

De Blasio flew to Atlanta after the interview to attend the Democratic National Committee winter meeting.

The meeting with de Blasio is regarded as the final step in the federal probe. A determination is expected shortly.