Michael Elston, chief of staff to Deputy Attorney General Paul McNulty, announced his decision Friday, The Washington Post reported. He plans to join a law firm.
Elston put together one list of U.S. attorneys being considered for dismissal. Four former U.S. attorneys also reported that he telephoned them to warn them against publicly discussing their dismissal.
John McKay, fired as U.S. attorney in Western Washington, told a congressional committee that Elston called him in January.
"My handwritten and dated notes of this call reflect that I believed Mr. Elston's tone was sinister and that he was prepared to threaten me further if he concluded I did not intend to continue to remain silent about my dismissal," McKay said.
McNulty and three other senior staff members have also resigned.