A former top National Security Council expert on Russia testified to Congress behind closed doors Monday, the latest ex-administration official to be subpoenaed as part of the House impeachment inquiry into President Trump.

Fiona Hill, 54, wouldn’t comment as she arrived on Capitol Hill, but her attorney said the British-born Harvard grad had received a congressional subpoena and would “comply and answer questions” from lawmakers.

And she was expected to tell lawmakers that the president’s personal lawyer, Rudy Giuliani, and the US ambassador to the European Union, Gordon Sondland, avoided her and the National Security Council process and ran their own Ukraine policy, CBS News and other media outlets reported.

Hill was also reportedly going to testify that she objected to Trump’s recall of former ambassador to Ukraine Marie Yovanovitch, but that her advice was ignored, according to the New York Times.

She resigned from the White House National Security Council over the summer.

Hill was the first White House official to appear as part of the House impeachment inquiry, and her appearance came despite a White House vow to halt any and all cooperation with what it termed the “illegitimate” impeachment probe.

The White House did not immediately respond to questions from the AP about whether they had sought to limit Hill’s testimony.

Republicans called on Rep. Adam Schiff, chairman of the House Intelligence Committee, to release transcripts of the depositions to the public.

The California Democrat said Sunday that having witnesses appear behind closed doors would prevent them from knowing what other witnesses said.

“We want to make sure that we meet the needs of the investigation and not give the president or his legal minions the opportunity to tailor their testimony and in some cases fabricate testimony to suit their interests,” Schiff said on CBS’s “Face the Nation.”

GOP Rep. Jim Jordan of Ohio, the top Republican on the House Oversight Committee, said he learned Monday morning that Schiff had subpoenaed Hill.

“She was going to come, she’d agreed to come, she was going to come voluntarily but he’s going to subpoena her, I believe, so he could ask certain questions and again keep those secret except for the certain things he wants to leak,” Jordan asserted.

“The tragedy here and the crime here is that the American people don’t get to see what’s going on in these sessions.”

Later this week, Sondland, an Oregon hotel magnate and Trump’s hand-picked ambassador to the EU, was expected to appear for a deposition against the wishes of the White House, after being subpoenaed.

He’s expected to tell Congress that his text message reassuring another envoy that there was no quid pro quo in their interactions with Ukraine was based on what Trump told him, according to a person familiar with his coming testimony in the impeachment probe.

Sondland’s appearance, set for Thursday, comes after a cache of text messages from top envoys provided a vivid account of their work acting as intermediaries around the time Trump urged Ukraine’s new president, Volodymr Zelensky, to launch investigations into a company linked to the family of Democratic rival Joe Biden.

One witness who may not be called before Congress is the still-anonymous government whistleblower who touched off the impeachment inquiry.

Top Democrats say testimony and evidence coming in from other witnesses, and even the president himself, are backing up the whistleblower’s account of what transpired during Trump’s July 25 phone call with Zelensky.

Lawmakers are concerned about protecting the person from Trump’s threats and may not wish to risk exposing the whistleblower’s identity.

But Trump strongly objected to keeping the whistleblower’s identity on the down low.

“Adam Schiff now doesn’t seem to want the Whistleblower to testify. NO!” the president tweeted early Monday. “We must determine the Whistleblower’s identity to determine WHY this was done to the USA.”

Sondland’s appearance comes after text messages from top ambassadors described their interactions leading up to Trump’s call and the aftermath.

He is set to tell lawmakers that he did understand the administration was offering Zelensky a White House visit in exchange for a public statement committing to investigations that Trump wanted, according to the person, who demanded anonymity to discuss remarks not yet given.

On Friday, Yovanovitch told lawmakers she was “incredulous” that the government had cut short her term as ambassador, “based, as best as I can tell, on unfounded and false claims by people with clearly questionable motives.”

She testified that she had been told by Deputy Secretary of State John Sullivan after being canned that the White House had conducted a campaign to oust her since the previous year, and that she had done nothing wrong.

Giuliani had told the president that Biden had quashed a Ukrainian investigation into a natural gas company that put his son Hunter Biden on its board of directors for as much as $50,000 a month.

The president and Giuliani had charged the Bidens with corruption.

There is no known evidence that either did anything wrong.