Before taking over the sprawling Justice Department investigation into foes of President Donald Trump, Joe diGenova decried the lack of progress in bringing indictments.

Five months later, diGenova has left his position without charging a single case, clouding the future of an investigation that has animated right-wing commentators eager to prove an ill-defined theory of a “deep state” conspiracy to take down the Republican president.

Justice Department officials are pressing forward despite diGenova’s departure, with a flurry of subpoenas to former law enforcement and intelligence officials expected to yield grand jury testimony in the weeks ahead at the Fort Pierce, Florida, home court of a favored Trump-appointed federal judge.

Yet whether anyone ultimately will be charged, and for what, remains an open question. Investigators face not only legal hurdles and personnel upheaval but an impatient White House after more than a year of fits and starts.

The investigation known familiarly as the “grand conspiracy” case is the clearest example yet of the Trump administration’s efforts to leverage law enforcement powers to enact retribution on the president’s adversaries. The tumult that has defined the probe exposes a familiar gap between White House demands for speedy action and the Justice Department’s ability to craft the president’s litany of grievances into a prosecutable case.

The investigation has always been a tough task, aiming to knit together separate FBI probes of Trump — including related to Russian election interference and his retention of classified documents at his Mar-a-Lago estate in Palm Beach, Florida — into a coherent narrative of a government conspiracy. Prior efforts to investigate the investigators have failed to uncover the kind of criminal misconduct the conspiracy probe aims to prove.

“The idea of connecting all those different investigations into one single conspiracy, there’s no basis for that,” retired federal prosecutor Randall Eliason said. “Then, maybe more importantly, there’s no basis for an allegation that any one of them was actually a criminal act against Trump. They’ve all been verified and upheld in one way or another.”

If the mandate is unusual, so, too, was the person picked to lead it. DiGenova, who’s 81, was a top prosecutor in President Ronald Reagan’s administration but had been out of government for decades. He made headlines in 2020 after he said a cybersecurity official who attested to the legitimacy of the election Trump lost to Democrat Joe Biden should be “drawn and quartered.” DiGenova apologized after being sued.

A prominent booster of the theory that Trump was victimized by a “deep state” conspiracy, diGenova was appointed in April shortly after Trump ousted Pam Bondi as attorney general after she struggled to prosecute his foes.

The appointment was heralded by Trump allies who regard the probe as a long-awaited reckoning for former officials they believe wronged the president. Attorney General Todd Blanche, who took the reins of the department after Bondi’s firing, also trumpeted diGenova’s arrival, writing on social media: “Welcome to the fight, Joe!”

By Sept. 10, diGenova was gone amid Trump administration frustration with the pace and management of the probe. His parting comments suggested he didn’t see a pathway for imminent indictments. “If you want indictments where there’s no evidence, you have an ethical problem,” he told the New York Post.

DiGenova told The Associated Press those comments were taken out of context, adding: “There’s plenty of evidence in all of these cases to prove the theories of prosecution. It just takes time to get there, and some people want to get there a little faster than others — and you can’t do that.”

DiGenova was sworn in days after a career national security prosecutor, Maria Medetis Long, was removed from the investigative team after conveying concerns about an investigation into former CIA Director John Brennan.