Byung “BJay” Pak, a former US attorney in Atlanta who abruptly quit during then-President Donald Trump‘s mission to overturn the results of the election, stepped down earlier than planned because he caught wind Trump was considering firing him, according to a source familiar with Pak’s interview with congressional investigators Wednesday.

The circumstances surrounding Pak’s departure were among the lingering mysteries from a chaotic stretch in early January. At the time, Trump and his allies were focused squarely on Georgia as they sought to push unfounded claims of mass election fraud. Two days before Pak’s resignation on January 4, Trump pressured Georgia Secretary of State Brad Raffensperger to validate bogus claims of election fraud in the state.

The Senate Judiciary Committee interviewed Pak on Wednesday as it investigates the pressure Trump put on the Justice Department to take a more active role in his efforts to overturn his electoral loss. The interview, which was not public, was conducted virtually and lasted between three and three and a half hours, according to the source familiar with the testimony.

Pak on Wednesday said it was not unreasonable for Trump to have concerns about election fraud in Georgia given the volume of allegations that the department received, the source said.

After Pak’s surprise resignation, Trump replaced him with his US attorney in Savannah, bypassing the normal chain of succession and raising suspicions about Pak’s departure.

Pak told the committee, according to the source familiar with his testimony, that he had confidence in his replacement at the US attorney’s office. He also acknowledged that he served at the pleasure of the president and could get fired at any time.

Documents released by the House in its investigation of Trump’s pressure on the Justice Department to substantiate his election fraud claims show Pak resigning after a key weekend in which Trump considered overhauling DOJ leadership because they hadn’t found widespread fraud.

Pak is one of six former DOJ political appointees whom the Biden administration green-lighted to talk to the committee about Trump’s election fraud push.

Trump’s move to then tap as Pak’s replacement Bobby Christine, another US attorney in Georgia, further arose suspicions about why Pak had resigned. Days earlier, Trump seemed to refer to Pak as a “never-Trumper” on his infamous January 2 call with Raffensperger.

Before his immediate resignation on January 4, Pak had told associates he had planned to stay on until the inauguration. It was later revealed, in reporting by The Wall Street Journal and The New York Times, that acting Deputy Attorney General Richard Donoghue had a phone call with Pak the night before his resignation. In that call, according to the Times, Donoghue relayed to Pak that the White House was frustrated with his failure to bring voter fraud investigations in the state. Pak himself has not said anything publicly about why he left his post earlier than planned.

By the afternoon of January 6, the shake-up had been overshadowed, first by Democrats’ dual wins in the Georgia special Senate elections, and then by the insurrection at the US Capitol.

Days later, Christine in a private call with the Atlanta’s office staff, told them that “there’s just nothing to” the election issues the office was looking into, according to the Atlanta Journal-Constitution.

A probe into Trump’s election reversal crusade picks up speed

The Senate committee has already spoken to two former Justice Department officials who witnessed key episodes in Trump’s pressure campaign. Donoghue spoke to the committee on Friday, and on Saturday, the committee had an interview with his former superior, Jeffrey Rosen, who served as Trump’s acting attorney general after William Barr stepped down in December.

Much of their testimony focused on the actions of Jeffrey Clark, another top Trump-appointee at the department who sought to get the department directly involved in Trump’s efforts to reverse the election results. Rosen’s testimony highlighted five episodes where Clark went out of the chain of command to push the fraud claims, a source familiar with the interview told CNN.

Senate Judiciary Chairman Dick Durbin announced the plans to interview Pak in comments to reporters on Capitol Hill Monday.

“It seems like slow going … but there is progress being made,” Durbin said.

Durbin has also indicated he wants to interview former Trump chief of staff Mark Meadows.

Hints of what happened before Pak’s departure

Clark’s escapades — which, as CNN reported, included the promotion of a false theory that China intelligence manipulated vote tallying machines with special thermometers — have attracted much of the attention as lawmakers in both the House and Senate investigate Trump’s interference at the department.

Pak, however, was referenced to in some of the internal Justice Department documents that have already been released by the House Oversight Committee.

On January 1, the day before the Trump-Raffensperger call, Rosen provided Pak’s cell phone number to Clark, according to the emails released by the committee. It was shared on an email chain titled “atlanta” where Clark alluded to his interest in a “video” that had been taken.

On January 3, the night of that Donoghue and Pak reportedly spoke on the phone, Donoghue emailed Pak with the request that he “Please call ASAP.”

Up until the dramatic early January episode, Pak had attracted little spotlight in his tenure leading Atlanta’s US attorney’s office. Before a stint as a Republican member of Georgia’s House of Representatives, he had also worked as an assistant US attorney in the Atlanta office. He had reputation in Georgia’s legal circles as being a straight shooter.

In addition to the formal resignation letters he submitted and the internal departure announcement to the Atlanta US Attorney’s office, Pak also sent an email to his fellow US attorneys on January 4, according to the documents released by House Oversight. In it, he said that, as a group, “they had made our country better, and safer, even though we were facing unprecedented challenges.”

FILE – In this Aug. 13, 2019, file photo, U.S. Attorney Byung J. “BJay” Pak is seen following a news conference in Atlanta. The Senate Judiciary Committee met privately Wednesday. Aug. 11, 2021, with the former U.S. Attorney in Georgia who resigned in January as former President Donald Trump waged a pressure campaign on state and federal officials to overturn his presidential defeat — part of a larger probe into Trump’s actions after the November election.(AP Photo/Ron Harris, File)