Joe DiGenova, the 81-year-old former U.S. attorney tapped to oversee the Justice Department's wide-ranging "grand conspiracy" investigation into alleged misconduct by Obama and Biden-era officials, resigned from his post on Thursday.

DiGenova turned in his resignation letter to Attorney General Todd Blanche at 3 p.m. on Thursday. In brief comments to multiple news outlets, he described the role as an honor and a privilege to serve President Trump and the department. His wife, attorney Victoria Toensing, who had also been working with the team of federal prosecutors in Fort Pierce, Florida, is expected to depart the Justice Department on Friday.

The resignation comes five months after DiGenova was brought in to lead the Florida-based probe. The investigation sought to link separate past inquiries into Trump, including the Russia interference assessment, the classified documents case, and efforts to challenge the 2020 election results, into a single criminal conspiracy framework. No charges have resulted from the effort to date.

DiGenova, who served as U.S. attorney for the District of Columbia during the Reagan administration and advised Trump during the Mueller investigation, had long publicly asserted that intelligence community actions against Trump constituted a politically motivated plot. He replaced a career prosecutor in the Southern District of Florida earlier this year after that official raised objections to advancing certain aspects of the case, such as scrutiny of former CIA Director John Brennan.

The probe operated under U.S. Attorney Jason A. Reding Quiñones and utilized a grand jury in Fort Pierce before Judge Aileen Cannon. DiGenova declined to elaborate on his reasons for stepping down when contacted by reporters. A person familiar with the matter cited frustration within the Justice Department and White House over the investigation's slow pace as a possible factor.

The abrupt departure leaves uncertainty around the future direction of the inquiry, which Trump allies have described as essential to addressing perceived abuses of power in prior administrations.