A top aide to US Attorney John Durham, who is probing the origins of the Trump-Russia investigation, has resigned from the Department of Justice, Fox News has confirmed.

A Justice Department source confirmed Friday that the federal prosecutor, Norah Dannehy, has resigned. Dannehy has worked with Durham for years and is a close aide to him.

Durham’s office confirmed that Dannehy resigned from the DOJ but did not elaborate on her reasoning. The Justice Department did not comment Friday.

Durham is the United States Attorney for the District of Connecticut. The Hartford Courant in Connecticut said Dannehy informed colleagues in the New Haven US Attorney’s Office of her resignation Thursday evening but did not elaborate on the reasons.

But the paper also cited sources in saying Dannehy resigned “at least partly out of concern that the investigative team is being pressed for political reasons to produce a report before its work is done.”

Her departure could complicate the final stretch of an investigation already slowed by the coronavirus pandemic but eagerly anticipated by President Donald Trump and his supporters to uncover what they see as wrongdoing within the FBI during the Russia investigation. It leaves the investigative team without one of its veteran prosecutors as key decisions presumably await before the probe wraps up.

Durham was appointed by Attorney General William Barr last year to investigate the origins of the FBI’s original Russia probe shortly after former Special Counsel Robert Mueller completed his yearslong investigation into whether the campaign colluded with the Russians to influence the 2016 presidential election.

In the year and a half since, he has questioned former law enforcement and intelligence officials — former CIA Director John Brennan among them — about decisions made during the course of the Russia probe. Dannehy had been a top leader on the team, present for interviews with such officials, including Brennan.

Durham’s timeline is focused on July 2016, when the FBI’s original Russia probe began, through the appointment of Mueller in May 2017.

Some Republicans have pushed for Durham to reveal his findings before November’s presidential election.

Trump himself has indicated that he wants results soon, saying at a White House press conference on Thursday that Durham was a “very, very respected man” and that his work would involve a “report or maybe it’s much more than that.”

The investigation has produced one criminal charge so far, against a former FBI lawyer accused of altering an email related to the surveillance of a former Trump campaign aide. But that prosecution did not allege a broader conspiracy within the FBI, and the conduct it involved had largely been laid out in a Justice Department inspector general report from last December.

It is not clear if Durham will be able to conclude his work before the election, though Barr has not ruled out the possibility of additional criminal charges.

Barr during an interview with 360aproko News this week said that there “could be” more charges stemming from Durham’s review.

“Yeah, there could be,” Barr said but declining to say whether any new charges would be announced prior to Election Day.