Two sources told NBC News that Brian Driscoll, who served as acting director at the beginning of Trump's term, was fired without explanation.
A senior FBI official who briefly served as acting director at the beginning of President Donald Trump's second term has been fired, two federal law enforcement sources told NBC News.
The official, Brian Driscoll, led the FBI at the start of the Trump administration and made headlines when he resisted a Justice Department directive to turn over a list of agents who'd worked on January 6 cases.
"This request encompasses thousands of employees across the country who have supported these investigative efforts," Driscoll wrote in a memo to FBI employees at the time. "I am one of those employees."
Driscoll, who'd been with the agency for almost 20 years, disclosed his firing in an email to colleagues, which was read to NBC News.
In it, he said he was not given any reason for his firing.
"Last night I was informed that tomorrow will be my last day in the FBI. I understand that you may have a lot of questions regarding why, for which I currently have no answers," the email said.
He added that "it has been the honor of my life to serve alongside each of you. Thank you for allowing me to stand on your shoulders throughout it all. Our collective sacrifices for those we serve is, and will always be, worth it. I regret nothing. You are my heroes and I remain in your debt."
Driscoll, who'd previously served on the FBI's Hostage Rescue Team and had been the agent-in-charge of the Newark Field Office, was named acting director while Trump nominee Kash Patel went through the confirmation process.
The request for thousands of names of FBI agents involved in investigating suspects who stormed the Capitol on January 6 came from then-Deputy Attorney General Emil Bove, who wrote in a memo that the list of names would be reviewed for any firing or "personnel actions."
"The FBI -- including the Bureau's prior leadership -- actively participated in what President Trump appropriately described as 'a grave national injustice that has been perpetrated on the American people over the last four years' with respect to events that occurred at or near the United States Capitol on January 6, 2021," Bove said.
Driscoll's resistance made him a hero within the rank-and-file members of the FBI, where there were fears that the list would be used to purge the FBI of agents who worked on Jan. 6 cases.
During his confirmation proceedings, Patel said, "I will honor the internal review process of the FBI." "All FBI employees will be protected against political retribution," he said in February.
The law enforcement sources said another senior official who's being fired is Steve Jensen, the assistant director in charge of the Washington Field Office who played a key role in the January 6 investigations.
Jensen, who also had a nearly 20-year career with the FBI, had previously served as the section chief of the Domestic Terrorism Operations Section at FBI Headquarters in Washington.
Jensen was originally scheduled to attend a Justice Department press conference Thursday at the U.S. Attorney's Office in DC to announce the indictment of the alleged shooter of two Israeli embassy staff members in May.
But Jensen did not show up, and U.S. Attorney Jeanine Pirro declined to answer questions about his departure.
The FBI Field Offices for Driscoll and Jensen declined to comment on either of the two firings, as did FBI headquarters.
A group representing FBI agents criticized the firings in a statement that suggested there had been additional terminations.
"The FBI Agents Association (FBIAA) is deeply concerned by reports that FBI Special Agents -- case agents and senior leaders alike -- are going to be summarily fired without due process for doing their jobs investigating potential federal crimes," the statement said.
"Agents are not given the option to pick and choose their cases, and these Agents carried out their assignments with professionalism and integrity. Most importantly, they followed the law."
The group said it is "reviewing all legal options to defend our members."
"If these Agents are fired without due process, it makes the American people less safe. Agents need to be focused on their work and not on potentially being illegally fired based on their assignments," the statement said.
A number of January 6 prosecutors have been fired by the Justice Department since Trump took office, and some have filed suit challenging the terminations.