House Democrats have subpoenaed four top aides to Secretary of State Mike Pompeo, saying that the Trump administration is stonewalling their investigation into the firing of the State Department’s top independent watchdog earlier this year.

Former State Department Inspector General Steve Linick appeared for a closed-door interview in the probe in June and told investigators that top department officials tried to bully him and dissuade his office from conducting a review of a multibillion-dollar arms sale to Saudi Arabia before he was fired.

Linick also said he was looking into previously reported allegations that Secretary of State Mike Pompeo and his wife may have misused government staff to run personal errands and several other matters. Trump abruptly fired him late on May 15 with what Linick said was no warning or cited cause.

Democrats announced Monday that they had subpoenaed the officials because they were “refusing to negotiate in good faith” and talk to the committee.

“That stonewalling has made today’s subpoenas necessary, and the committees will continue to pursue this investigation to uncover the truth that the American people deserve,” said House Foreign Affairs Committee Chairman Eliot Engel, D-N.Y., House Oversight and Reform Committee Chairwoman Carolyn Maloney, D-N.Y., and the top Democrat on the Senate Foreign Relations Committee, New Jersey Sen. Robert Menendez.

The subpoenas for closed-door depositions are for Under Secretary of State for Management Brian Bulatao, Acting State Department Legal Adviser Marik String, Deputy Assistant Secretary of State for Political-Military Affairs Michael Miller and Senior Adviser Toni A. Porter. The State Department had no immediate comment on the subpoenas.

Pompeo has rejected allegations that Linick was fired for investigating alleged impropriety and denied he was aware of any such probe into his or his wife’s affairs. He has said Linick was removed for not doing his job.

Linick, who had been inspector general since 2013, said he was in a “state of shock” when he was fired. He told the committees that he had opened a review of last year’s $8 billion arms sale to Saudi Arabia at the request of lawmakers who claimed Pompeo had inappropriately circumvented Congress to approve the deal. He said Bulatao and String then tried to stop him.

In the statement announcing the subpoenas, the Democrats said they had also interviewed a separate State Department official, Charles Faulkner, and that interview “raises additional questions” about the Saudi arms sale.

Pompeo, Bulatao and others have said Linick was dismissed in part because of the alleged leak of one of his office’s reports into accusations of political reprisals by Trump appointees against career State Department officials. Linick denied his office was responsible for the leak and said an investigation by the Defense Department inspector general cleared him and his office.

(AP)