The House Judiciary Committee issued subpoenas Tuesday for the testimony of two Justice Department officials, including one of former special counsel Robert S. Mueller III’s top prosecutors, in its probe of what panel Democrats call the agency’s “unprecedented politicization” under President Trump and Attorney General William P. Barr.

The committee’s chairman, Rep. Jerrold Nadler (D-N.Y.), issued a summons to Aaron Zelinsky, who worked on the team prosecuting Trump’s friend Roger Stone and resigned from the case in protest after being forced to seek a lesser prison sentence following the president’s complaints.

In a statement, Nadler said that Zelinsky would appear at a hearing scheduled for June 24 alongside John Elias, acting chief of staff of the Justice Department’s Antitrust Division, to whom the committee also issued a subpoena Tuesday.

Nadler said they want to hear from Zelinksy, now with U.S. Attorney’s Office in Maryland, about the handling of Stone’s case. Elias is expected to face questions about “improperly motivated activity by the Antitrust Division,” the news release said. The New York Times, which first reported on the subpoenas, noted he had purview of the department’s now-abandoned inquiry into a pact between the state of California and several automakers — a deal similarly attacked by the president.

Robert Litt, an attorney for Zelinksy, said his client intends to comply with the subpoena “and testify to the extent appropriate.” Attempts to reach Elias were not immediately successful.

Donald Ayer, a former deputy attorney general who preceded Barr in that role during the George H.W. Bush administration, also will testify, though he was not subpoenaed, Nadler said. Ayer has publicly called on Barr to step down.

In an interview Tuesday, he said he plans to detail for the committee how, as attorney general, Barr has been “increasing the powers of the president to the point that he’s almost an autocrat,” noting that “it’s not too strong to say that Mr. Barr is working to dismantle many if not most of the reforms” put in place after the Watergate scandal that led to Richard M. Nixon’s resignation as president. Barr always had those ideas, Ayer added. “It’s just that now with the president being who he is, [Barr] is in a position to move ahead.”

A spokeswoman for the Justice Department declined to comment.

Nadler’s announcement comes as two Republican-led Senate committees conduct investigations into the Justice Department, inquiries focused on the origins of the FBI’s probe of Trump’s 2016 campaign and Russia’s interference in that year’s election. Last week, the Senate Judiciary Committee voted to give its chairman, Sen. Lindsey O. Graham (R-S.C.), sweeping power to issue subpoenas to former Obama administration officials in the course of its probe; earlier this month, the Senate Homeland Security Committee gave its chairman, Sen. Ron Johnson (R-Wis.), authority to do the same.

While the Senate investigations are focused on highlighting the biases of and mistakes made by career law enforcement officials, Nadler’s probe concerns what Democrats consider efforts by the White House and by Barr to compromise the Justice Department’s independence.

Nadler accused Barr of catering to “President Trump’s private political interests, at the expense of the American people and the rule of law.” He also criticized the attorney general for having “abdicated his responsibility to Congress” by failing to appear before the Judiciary Committee. A March hearing with Barr to discuss politicization at the Justice Department was scrapped due to the coronavirus crisis.

The tactic of subpoenaing Justice Department officials still working for the Trump administration resembles Democrats’ strategy during last year’s impeachment proceedings, when House investigators issued summonses to witnesses from the State Department and the Defense Department as a means to circumvent internal resistance to them testifying. The subpoenas for Zelinsky and Elias, however, were announced more than a week before their scheduled testimony whereas those issued during the impeachment inquiry usually were signed at the last minute.