WASHINGTON, D.C. (NEXSTAR) — Another key witness for Democrats testified on Capitol Hill Friday morning.

Former Ambassador to Ukraine Marie Yovanovitch appeared for a closed-door hearing aimed at shedding more light on President Donald Trump’s alleged dealings with the Ukranian president.

Until the moment Yovanovitch arrived, it wasn’t clear whether she’d actually testify.

Trump hinted this week he’d block the career diplomat from talking.

“I just don’t think that you can have all these people testifying about every conversation you’ve had,” Trump said.

Trump ousted Yovanovitch as ambassador to Ukraine in May, allegedly after hearing she’d been speaking out against him.

According to reporting today by The New York Times and The Washington Post, Yovanovitch denied that during her testimony Friday, telling lawmakers she was “incredulous” at being removed for “unfounded and false claims.”

Lawmakers on the House panels grilling Yovanovitch were notably quiet, although some did give insight into what it was she was saying.

“She is apparently as apolitical as I’ve heard anyone,” said Rep. Eleanor Holmes Norton (D-D.C.). “So far, I think both sides are finding her very credible.

House Democrats hope to learn more from Yovanovitch about whether the President pressured Ukraine to investigate Joe Biden in exchange for military aid.

It’s expected that other current and former State Department officials will appear before congressional investigators in the coming weeks.