Joe diGenova, the 81-year-old Trump loyalist who had headed a sprawling investigation in the Southern District of Florida that targeted President Donald Trump’s perceived political enemies, has resigned from the Justice Department.

“It was an honor and a privilege to serve the president and the department,” diGenova said Thursday.

Asked about the reason for his departure, diGenova declined to comment.

“I’m moving on,” diGenova said.

ABC News was first to report on diGenova’s departure.

While diGenova resigned from the DOJ and was not fired, a source familiar with the determination told NBC News that Justice Department officials had already lost confidence in his leadership skills and ability to run the investigation.

DOJ leadership felt the investigation was not moving quickly enough, even though diGenova was provided with a team of Justice Department lawyers from Washington, per the source familiar with the determination, who said the hope is the probe can get back on track with those attorneys at the helm.

For now, a specific person will not be named to take over diGenova’s place, and the investigation is expected to move forward without delays.

The Justice Department declined to comment on diGenova’s resignation.

DiGenova, a top federal prosecutor under President Ronald Reagan, was part of Trump’s efforts to overturn the 2020 election in his favor. The attorney made headlines earlier this year after it was revealed that he would head the Florida-based investigation into Trump’s foes.

DiGenova’s probes have not produced any prosecutions. Though shortly before his resignation there was a recent burst of activity in the wide-spanning probe. The Justice Department is seeking testimony from multiple former officials before a federal grand jury, people familiar with the probes told NBC News. The Associated Press first reported on the subpoena activity.

The probe reached back a decade, revisiting a DOJ inquiry into Russian interference in the 2016 presidential election. That posed a major hurdle for the investigation, given that activity took place nearly a decade ago, far outside the typical five-year statute of limitations for most federal crimes.

DiGenova stepped in to replace career prosecutor Maria Medetis Long, who had objected to advancing an investigation into former CIA Director John Brennan, whom Trump allies were pushing to be charged for allegedly false testimony.

The grand conspiracy investigation was taking place in a legal district that has historically been advantageous for Trump, overseen by Trump-appointed U.S. Attorney for the Southern District of Florida Jason A. Reding Quiñones, and using a grand jury in a Fort Pierce court run by U.S. District Judge Aileen Cannon, a Trump-friendly judge.

DiGenova was appointed to the role in April by then-acting Attorney General Todd Blanche, shortly after Pam Bondi was fired. The lawyer, along with Rudy Giuliani and Sidney Powell, as well as his wife, Victoria Toensing, whom diGenova brought into his DOJ team, was part of a group that repeatedly attempted and failed to overturn Trump’s 2020 election loss.