During his years as the top federal prosecutor in Pittsburgh, David J. Hickton said, there was always a “very clear” line between policy direction from Washington and interference from the White House.

But in recent days, he said, that line appears to have disappeared.

Hickton, an appointee of President Barack Obama who served from 2010 to 2016, is among more than 2,000 former Justice Department employees who have signed on since Saturday to a public letter calling on Attorney General William Barr to resign.

The group — including more than a dozen past federal prosecutors from Pennsylvania and New Jersey — criticized his handling of the case against President Donald Trump’s longtime friend Roger Stone. They exhorted current department employees to report unethical conduct and prepare, if necessary, to leave their jobs in protest.

“The line between permissible policy direction by the administration and impermissible illegal political interference is very clear,” Hickton said Monday. “It has been crossed here. What’s going on is clearly illegal.”

That groundswell from alumni is the latest sign that the Justice Department’s handling of the Stone case has ignited a crisis of confidence among many of its former employees and affected morale among career prosecutors across the country.

On Tuesday, a national association of sitting federal judges is expected to convene an emergency meeting to address similar concerns, its president, Philadelphia-based U.S. District Judge Cynthia M. Rufe, said.

“There are plenty of issues that we are concerned about,” Rufe, a George W. Bush appointee, told USA Today. “We’ll talk all of this through.”

The list of former employees from U.S. Attorney’s Offices in Pennsylvania and New Jersey who signed this weekend’s letter includes registered Republicans and Democrats, career prosecutors and political appointees — some stretching back as far as the Carter administration.

Among the signatories are Peter J. Smith and Paul Fishman — Obama’s top federal prosecutors in Harrisburg and New Jersey, respectively — as well as Michael Levy, who twice served as interim U.S. attorney in Philadelphia, once each under Obama and Bush.

Many of those who signed said they had worked under Barr during his first stint as attorney general in the early ‘90s during the George H.W. Bush administration.

They said they had been hopeful when he was renominated for the post in 2018 that he would restore steady, apolitical stewardship to an office that had become a frequent presidential punching bag during special counsel Robert Mueller’s investigation into Russian interference in the 2016 election.

Barr “behaved extraordinarily professionally back then,” said Barry Gross, who served more than two decades as an assistant U.S. attorney in Philadelphia and is now a partner at the Center City offices of law firm Faegre Drinker Biddle & Reath.

But the attorney general’s public defense of Trump after the publication of Mueller’s report last year and his actions in the Stone case last week have caused some former colleagues to question whether he has gone too far in protecting the president and his allies.

Stone, a top adviser to Trump’s 2016 campaign, faces sentencing this week after his November conviction for lying to Congress and obstruction of justice.

The four line prosecutors who tried the case had originally recommended a prison sentence of seven to nine years. But after the president publicly attacked their recommendation on Twitter, the Justice Department, at Barr’s urging, filed an updated sentencing memo suggesting Stone should receive a lighter sentence.

Barr has said he did not talk to the president about the Stone sentence — a claim that drew skepticism from DOJ alumni in their Sunday letter.

“Mr. Barr’s actions in doing the president’s personal bidding unfortunately speak louder than his words,” it read. “Those actions, and the damage they have done to the Department of Justice’s reputation for integrity and the rule of law, require Mr. Barr to resign.”

All four of the prosecutors originally assigned to Stone’s case withdrew from the case in protest. One of them, Jonathan Kravis, resigned from the department. He had been a traveling DOJ trial attorney assigned to prosecute cases across the country and had a hand in many of Philadelphia’s most notable public corruption cases in recent years.

Kravis was part of the team that secured the 2016 conviction against former Democratic U.S. Rep. Chaka Fattah on bribery and corruption charges. He also led the trial prosecution of State Sen. Larry Farnese, who was acquitted in 2017 of bribery charges, and helped build the case that sent two of former U.S. Rep. Bob Brady’s top advisers to prison for campaign violations last year.

Gross, who faced off against Kravis in court representing one of Fattah’s codefendants, praised his decision to leave the Stone case and his job.

“Even though I fought him in court and took a completely different view of the evidence, I found him to be 100% professional, ethical, and a really bright guy,” Gross said. “I applaud him for what he did here.”

Fattah’s case was also disrupted last year when intervention from Justice Department officials in Washington sewed division with the local federal prosecutors who had secured the former congressman’s conviction.

Last year, the U.S. Attorney’s Office filed a sentencing recommendation seeking at least two years’ incarceration for former Philadelphia Deputy Mayor Herbert Vederman, who had been accused of bribing Fattah for years. But Vederman’s lawyers took their campaign to Justice Department officials in Washington, and just before sentencing, the department filed a new sentencing recommendation asking for one year behind bars.

The move so upset the local team that had originally tried the case that they boycotted Vederman’s sentencing hearing in protest. But Levy, the former interim U.S. attorney from Philadelphia who also spent three decades as a line prosecutor before retiring last year, drew a distinction between what happened in that case and in Stone’s.

“That was a fight over the merits” of differing opinions, he said. “The Trump administration didn’t put their thumb on the scale for a friend.”

Barr has not responded to Sunday’s letter, and Justice Department officials did not return requests for comment on Monday.

Levy, like the other signatories, said he wasn’t holding out hope that the attorney general will heed their call to step down.

And even if he does, Levy said, “be careful what you wish for. You don’t know who could come next.”