Yovanovich's statement represented a top-to-bottom rebuke of the president, his associates, and his foreign policy — a rare takedown from a career diplomat who has sought to avoid the spotlight ever since her ouster. Yovanovitch expressed her “deep disappointment and dismay” at efforts to undermine trust in American institutions, and warned that “this nation’s most loyal and talented public servants” are running for the exits. She also said other countries would likely exploit the same dynamic that led to her ouster to undermine U.S. foreign policy.

Yovanovitch, who remains a State Department employee, was the latest firsthand witness to testify about Trump's interactions with Ukraine, as he ramped up efforts to pressure the country's new president to investigate former Vice President Joe Biden, a 2020 contender.

The chairs of the three House committees leading the investigation said the State Department and the White House had ordered Yovanovitch not to attend, prompting them to issue a subpoena. Yovanovitch, they said, agreed to comply with the subpoena over her agency's objections, sitting for more than nine hours behind closed doors on Friday.

“Any efforts by Trump administration officials to prevent witness cooperation with the committees will be deemed obstruction of a co-equal branch of government and an adverse inference may be drawn against the president on the underlying allegations of corruption and cover-up,” said Intelligence Committee Chairman Adam Schiff (D-Calif.), Foreign Affairs Committee Chairman Eliot Engel (D-N.Y.) and Oversight Committee Chairman Elijah Cummings (D-Md.).

Unlike the most recent witness in the Ukraine matter to testify — Kurt Volker, the former U.S. special representative for Ukraine negotiations — Yovanovitch is still employed by the State Department, which raises questions about whether she will face punishment for defying orders. Legal experts and State Department officials have been trying to resolve the question of whether a congressional subpoena trumps a State Department direction to a Foreign Service officer.

“Her willingness when served with compulsory process to follow the law and testify — I think she is a courageous example for others,” Schiff told reporters.

According to her statement, Yovanovitch was told “abruptly” in late April to return to Washington “on the next plane.” Her removal came amid a campaign by Trump’s allies to accuse her of disloyalty, a charge she said was “fictitious.” Trump himself attacked Yovanovitch during a phone call with Ukraine's newly elected president Volodymyr Zelensky on July 25, which is at the center of Democrats’ impeachment inquiry. Trump referred to her as “bad news," according to a summary of the conversation released by the White House. He also said, without elaboration, that she was “going to go through some things.”

Yovanovitch's appearance on Capitol Hill Friday was a breakthrough for House Democrats seeking firsthand details about Trump's efforts — both directly and through his personal attorney Rudy Giuliani — to pressure Ukraine's leaders to investigate Biden.

Yovanovitch said she had “minimal contacts” with Giuliani, adding: “I do not know Mr. Giuliani’s motives for attacking me.” She speculated that Giuliani’s associates “believed that their personal financial ambitions were stymied by our anti-corruption policy in Ukraine.”

She also said U.S. interests are “harmed” when “private interests circumvent professional diplomats for their own gain, not the public good.” It appeared to be a reference to Giuliani’s efforts to leverage government officials to dig up dirt on Biden.

“The harm will come when bad actors in countries beyond Ukraine see how easy it is to use fiction and innuendo to manipulate our system,” she said in her opening statement. “In such circumstances, the only interests that will be served are those of our strategic adversaries, like Russia, that spread chaos and attack the institutions and norms that the U.S. helped create and which we have benefited from for the last 75 years.”

According to Rep. Sean Patrick Maloney (D-N.Y.), an Intelligence Committee member, Yovanovitch at times “became overcome with emotion and had to stop and leave the room before recounting how she was thrown to the wolves.” He said Yovanovitch’s testimony “detailed a shocking abuse of presidential power.”

“It is clear to me that she was fired because she was a thorn in the side of those who sought to use the Ukrainian government for their own political and financial gain — and that includes President Trump,” Maloney added.

Some of the president’s closest Republican allies who sit on the committees spearheading the inquiry attended Yovanovitch’s deposition, including Ohio Rep. Jim Jordan and North Carolina Rep. Mark Meadows. After the deposition concluded, they defended Trump from Yovanovitch’s charges and harangued Democrats for crafting a process whereby lawmakers are prohibited from discussing the substance of the testimony in public.

“The president of the United States is entitled to have the ambassador ... he wants in that position,” Jordan said.

The State Department’s inspector general last Wednesday briefed congressional aides about an apparent attempt to smear the veteran civil servant. Two foreign-born associates of Giuliani — both indicted Thursday on campaign finance charges — have also been accused of seeking her removal at the behest of an unnamed Ukrainian government official.

Yovanovitch is a highly regarded diplomat within the U.S. foreign policy establishment. At the State Department, her treatment has unnerved many staffers, especially in the division that handles Europe. It also has damaged the standing of Secretary of State Mike Pompeo, who has been unwilling to publicly defend Yovanovitch.

Morale in the department was rattled even further this week after it was announced that Mike McKinley, a veteran career diplomat who serves as a top adviser to Pompeo, was resigning. The reasons for his departure, confirmed to POLITICO by a senior Trump administration official, were not clear, but the timing is not helping the morale, people in the department say.

Yovanovitch said in her opening statement that the State Department has been “attacked and hollowed out from within.”

Just as Yovanovitch agreed to testify, Trump’s representative to the European Union, Gordon Sondland, announced Friday morning that he would sit for a deposition next week, after similarly receiving a congressional subpoena.

“Notwithstanding the State Department’s current direction to not testify, Ambassador Sondland will honor the Committees’ subpoena, and he looks forward to testifying on Thursday,” his attorneys said in a statement.

But Sondland’s lawyers also said he would not be able to comply with House Democrats’ subpoena for documents, saying that “federal law and State Department regulations prohibit him from producing documents concerning his official responsibilities.” Some Republicans have been eager to let Sondland, a firm Trump ally, testify in a bid to buttress Trump's position.

Harold Koh, a former State Department legal adviser, said his interpretation is that a congressional subpoena would outweigh a State Department directive. He noted that it’s also possible that, facing such a situation, State could order a staffer to limit his or her testimony, for example, by not discussing classified information.

It's not clear if State will or even would be allowed to punish Yovanovitch. But sometimes such punishments are veiled. Yovanovitch could find herself given low-ranking assignments in the future, with no official reason as to why. There already are at least two ongoing federal investigations into whether, under Trump, State Department career employees have been victims of political retaliation, including being given low-level roles.

The State Department did not respond to a query Friday as to whether Yovanovitch or Sondland would face punishments.

Sondland's name emerged in a series of text messages provided to House investigators by Volker, the former U.S. special representative for Ukraine negotiations who resigned days before testifying last week. In the text chain, Sondland, Volker and Bill Taylor — currently the top U.S. envoy in Ukraine — discussed apparent efforts by Trump and Giuliani to pressure Ukraine to investigate Biden, perhaps by withholding a planned White House visit or military aid.

Yovanovitch said she was not involved in discussions about Trump’s July 25 call with Zelensky, or about the military aid, which was temporarily withheld earlier this year. House Democrats are examining whether the critical funds were frozen as a way to convince Zelensky to target Trump’s political rovals.

Volker, Sondland and Yovanovitch were among several senior State Department officials listed in a schedule of depositions that accompanied a subpoena for documents delivered late last month to Pompeo by the three House Democratic chairmen leading the impeachment probe.

Pompeo rebuffed the committee leaders in a letter last Tuesday, signaling that he would not comply with their requests and writing that he would “use all means at my disposal to prevent and expose any attempts to intimidate the dedicated professionals whom I am proud to lead and serve alongside at the Department of State.”

Quint Forgey contributed to this story.