In an email to F.B.I. employees, Mr. Driscoll said the acting attorney general had asked Mr. Kissane to fill the deputy role. Mr. Driscoll said he looked forward to working with Mr. Kissane over the “course of the transition to ensure the F.B.I.’s critical mission to protect the American people and uphold the Constitution continues.” The decision to elevate Mr. Driscoll and Mr. Kissane to the seventh floor of bureau headquarters where senior leadership sits signals that the Trump administration wanted a clean break after lengthy F.B.I. investigations that ensnared the president.

It has been a busy couple of days at the FBI, as a recent appointment by President Donald Trump gives the agency its third head in less than 48 hours. The appointment comes after the FBI’s acting director unexpectedly retired Monday, Jan. 20. Brian Driscoll, recently appointed head of the FBI’s field office in Newark, New Jersey, will now run the agency on an interim basis, according to an announcement by the Trump administration on Monday.

According to the FBI website, Driscoll became a special agent in 2007. He has experience working in the agency's New York field office and also worked on the FBI's SWAT team. The White House's announcement came shortly after FBI acting director Paul Abbate retired on Monday, reportedly just minutes before Trump took office. Christopher Wray stepped down from the agency on Sunday, and Abbate only held down the acting director post for a day.