In December, Donald J. Trump, then the president-elect, said he would consider pardoning Mr. Adams, who was facing federal corruption charges.

After Mr. Trump took office, Mr. Adams’s lawyers asked the White House if Mr. Trump would pardon the mayor, who had not yet faced trial.

A week later, Emil Bove III, Mr. Trump’s former criminal defense lawyer who is now the Justice Department’s acting No. 2 official, called Mr. Adams’s lawyer. He said he wanted to talk about the possibility of dismissing the case.

Mr. Bove then sent a memo to the Southern District of New York, ordering prosecutors to dismiss charges against Mr. Adams.

The interim U.S. attorney for the Southern District, Danielle R. Sassoon, resigned rather than obey Mr. Bove’s order.

Mr. Bove referred the case to the Justice Department’s Public Integrity Section in Washington.

And the two men in charge of that unit, Kevin O. Driscoll and John Keller, resigned.

Hours later, three more lawyers in the public integrity section resigned.

The next morning, the lead prosecutor on the case, Hagan Scotten, announced his resignation from the Southern District.

In December, Donald J. Trump, then the president-elect, said he would consider pardoning Mr. Adams, who was facing federal corruption charges.

After Mr. Trump took office, Mr. Adams’s lawyers asked the White House if Mr. Trump would pardon the mayor, who had not yet faced trial.

A week later, Emil Bove III, Mr. Trump’s former criminal defense lawyer who is now the Justice Department’s acting No. 2 official, called Mr. Adams’s lawyer. He said he wanted to talk about the possibility of dismissing the case.

Mr. Bove then sent a memo to the Southern District of New York, ordering prosecutors to dismiss charges against Mr. Adams.

The interim U.S. attorney for the Southern District, Danielle R. Sassoon, resigned rather than obey Mr. Bove’s order.

Mr. Bove referred the case to the Justice Department’s Public Integrity Section in Washington.

And the two men in charge of that unit, Kevin O. Driscoll and John Keller, resigned.

Hours later, three more lawyers in the public integrity section resigned.

The next morning, the lead prosecutor on the case, Hagan Scotten, announced his resignation from the Southern District.

In December, Donald J. Trump, then the president-elect, said he would consider pardoning Mr. Adams, who was facing federal corruption charges.

After Mr. Trump took office, Mr. Adams’s lawyers asked the White House if Mr. Trump would pardon the mayor, who had not yet faced trial.

A week later, Emil Bove III, Mr. Trump’s former criminal defense lawyer who is now the Justice Department’s acting No. 2 official, called Mr. Adams’s lawyer. He said he wanted to talk about the possibility of dismissing the case.

Mr. Bove then sent a memo to the Southern District of New York, ordering prosecutors to dismiss charges against Mr. Adams.

The interim U.S. attorney for the Southern District, Danielle R. Sassoon, resigned rather than obey Mr. Bove’s order.

Mr. Bove referred the case to the Justice Department’s Public Integrity Section in Washington.

And the two men in charge of that unit, Kevin O. Driscoll and John Keller, resigned.

Hours later, three more lawyers in the public integrity section resigned.

The next morning, the lead prosecutor on the case, Hagan Scotten, announced his resignation from the Southern District.

In December, Donald J. Trump, then the president-elect, said he would consider pardoning Mr. Adams, who was facing federal corruption charges.

After Mr. Trump took office, Mr. Adams’s lawyers asked the White House if Mr. Trump would pardon the mayor, who had not yet faced trial.

A week later, Emil Bove III, Mr. Trump’s former criminal defense lawyer who is now the Justice Department’s acting No. 2 official, called Mr. Adams’s lawyer. He said he wanted to talk about the possibility of dismissing the case.

Mr. Bove then sent a memo to the Southern District of New York, ordering prosecutors to dismiss charges against Mr. Adams.

The interim U.S. attorney for the Southern District, Danielle R. Sassoon, resigned rather than obey Mr. Bove’s order.

Mr. Bove referred the case to the Justice Department’s Public Integrity Section in Washington.

And the two men in charge of that unit, Kevin O. Driscoll and John Keller, resigned.

Hours later, three more lawyers in the public integrity section resigned.

The next morning, the lead prosecutor on the case, Hagan Scotten, announced his resignation from the Southern District.