House Democrats’ impeachment investigators left a nine-hour interview on Friday with the former U.S. ambassador to Ukraine, Marie Yovanovitch, empowered—an elusive feeling for them so far—and optimistic they will get the witnesses and documents they need to build a case for impeaching President Trump in the face of stonewalling from his administration.

The State Department had issued strict orders blocking Yovanovitch from testifying before lawmakers. She defied that order on Friday, given a bit of cover thanks to a last-minute subpoena from Democrats. That has Democrats hopeful her stand will be contagious, spreading to the numerous other witnesses who have been asked to testify in the impeachment inquiry.

Rep. Tom Malinowski (D-NJ), himself a former State Department official, left the briefing saying that Yovanovitch was a person of “rare” integrity. “Her appearance here is very important and establishes that legally binding subpoenas not only should be but can be respected,” he said.

If Malinowski is right, that’s a significant boost for Democrats: over the next several weeks, they have teed up subpoenas and requests for testimony and documents for a wide range of figures implicated in the impeachment inquiry, from Vice President Mike Pence to Energy Secretary Rick Perry and Rudy Giuliani.

In the next week alone, investigators will hear from Fiona Hill, the former top official for Russia on the National Security Council, along with several others who had previously been blocked from testifying, including Gordon Sondland, the U.S. ambassador to the European Union who is a central player in the Ukraine probe.

In a letter to House members sent on Friday, House Intelligence Committee Chairman Adam Schiff (D-CA) spelled out how Democrats would respond to not getting what they’re asking for, raising the notion that any obstruction would constitute an impeachable offense by itself.

“The White House’s attempt to stonewall is lawless, and as we have stated from the outset, efforts to hide the truth of the President’s abuse of power will be considered as evidence of obstruction of the impeachment inquiry and also an adverse inference may be drawn against the President on the underlying allegations of corruption and its cover up,” Schiff wrote.

Against that backdrop, the fact that Yovanovitch testified at all is a key win for Democrats as they head into this crucial stretch for impeachment. But lawmakers were largely quiet on the substance of her testimony, leaving questions about how significant it was to their inquiry.

What she said in her “transcribed interview”—not technically a deposition—is not yet known. But a member of Congress familiar with her testimony told The Daily Beast that “today was not a monumental day for the impeachment inquiry, and the ambassador's opening statement was probably the most damning thing she said all day.”

“The ambassador was gone by May of 2019, so any opinion on impeachment would all be based on what she’s read in the media, not from firsthand knowledge,” the lawmaker said.

Democrats had harbored high expectations for the testimony of Yovanovitch, who served as the top American official in Ukraine from August 2016 until May 2019, when she was recalled from Kyiv by the Trump administration. Reportedly considered an obstacle by Trumpworld to their designs on Ukraine—particularly the president’s desire for them to investigate a political rival, former Vice President Joe Biden—Yovanovitch was positioned to shed light on the extent of that contact and also to push back on unsubstantiated rumors circulating that she was anti-Trump or corrupt herself.

Rep. Denny Heck (D-WA), a member of the House Intelligence Committee, declined to say much about the substance of her remarks but seemed awestruck. “I just spent eight hours and it went like a New York second,” he told reporters. “It was that amazing, that powerful.”

The public’s only glimpse into Yovanovitch’s marathon hearing was her prepared opening statement, which were published by several news outlets shortly after the hearing began. In those remarks, she categorically debunked the claims circulating about her from allies of the president—and the president himself, who called the ambassador “bad news” in his August phone call with the Ukrainian president.

The longtime diplomat told lawmakers she felt “deep disappointment and dismay” at the “smear campaign” designed to force her removal—reportedly urged on enthusiastically by Giuliani and others who sought to remove an obstacle to their Ukraine plans—and defended her impartiality.

Yovanovitch said she was “incredulous” that the administration “chose to remove an ambassador based, as best I can tell, on unfounded and false claims by people with clearly questionable motives.”

It is unclear if or when Democrats will release any portions of her remarks or any evidence she may have provided. In brief remarks Friday night, Schiff declined to answer questions about when that information would be public.

Moments before, Republican lawmakers hammered Schiff for holding the hearing behind closed doors as they demanded that the impeachment inquiry be held in front of the cameras—or that the chairman at least release transcripts of the interviews.

— with reporting from Betsy Swan