A US attorney overseeing the so-called “grand conspiracy” investigation into Donald Trump’s rivals announced on Friday he is leaving the Department of Justice, one of several officials to leave the department in recent days after sweeping Democratic wins in the midterm elections.

Jason Reding Quiñones, the US attorney for the southern district of Florida, and John Eisenberg, who led the justice department’s national security division, are both leaving. Democrats have pledged to use their majorities in the US House and Senate to conduct aggressive oversight of the justice department, among other agencies.

Quiñones had been overseeing an inquiry into whether former top government officials engaged in a “grand conspiracy” to violate Trump’s rights when they investigated him after the 2020 election. Conservative allies had high hopes for the investigation, whose targets included the former CIA director John Brennan, among others.

But there were personnel issues and charges have not yet been filed. “The ‘grand conspiracy’ case into the lawfare against the president is essentially dead now,” Julie Kelly, a conservative commentator, posted on X.

“We are grateful for Jason’s leadership in combating violent crime, drug trafficking, sex trafficking and transnational crime, including the indictment of Raúl Castro,” the US attorney general, Todd Blanche, said in a statement.

Eisenberg led the national security division, which oversees terrorism and espionage cases, among others. Eisenberg had previously served in the first Trump administration and has been a top lawyer for the national security council. “He has served with distinction, strengthening our nation’s ability to address threats, both foreign and domestic,” Blanche said in a post on X.

Harmeet Dhillon, the controversial head of the justice department’s civil rights division, also announced she was leaving on Thursday. Dhillon had sought to leave before the midterms and was asked by the White House chief of staff, Susie Wiles, to stay on until after election day.

CBS News reported on Thursday that Trump sought to dismiss Dhillon after her October appearance on 60 Minutes for not more forcefully defending efforts to prosecute non-citizens and send monitors to the polls.

Dhillon told the Guardian she submitted her resignation letter on 13 October, before the 60 Minutes interview aired, and that Wiles asked her to stay on until at least early November. She had also indicated to reporters in August she intended to return to private practice when she left the justice department, according to Bloomberg.