Marie Yovanovitch has been a key player in the impeachment inquiry for many reasons.
Yovanovitch, a career diplomat who's been in public service for over three decades and is widely respected in the State Department, was recalled as the US ambassador to Ukraine in May after becoming the target of a smear campaign led by President Donald Trump's personal lawyer, Rudy Giuliani.
Giuliani has been heavily implicated in the impeachment inquiry and characterized as the tip of the spear in a shadowy effort to leverage US foreign policy and pressure Ukraine into launching investigations that would help Trump. Based on testimony from Yovanovitch and other witnesses, she essentially became collateral damage in the process.
Yovanovitch, still a State Department employee, was the first sitting government official who appeared for a closed-door deposition in the impeachment inquiry. In doing so, she defied the Trump administration's orders for federal employees to not take part in the inquiry.
In mid-November, Yovanovitch publicly testified to the House Intelligence Committee that she was "kneecapped" by Americans who were willing to partner with corrupt Ukrainians in pushing a disinformation campaign that ultimately resulted in her being removed as ambassador.
"Working together, they apparently succeeded in orchestrating the removal of a US ambassador," Yovanovitch said.
"How could our system fail like this? How is it that foreign corrupt interests can manipulate our government?" she added. "Which country's interests are served when the very corrupt behavior we have been criticizing is allowed to prevail?"
Yovanovitch painted a scathing portrait of Giuliani, testifying that he allied with dubious Ukrainians threatened by her record as an anti-corruption crusader. She forcefully rejected allegations by Trump's allies, including Giuliani, that she harbored bias against the president.
"Mr. Giuliani should have known those claims were suspect, coming as they reportedly did from individuals with questionable motives and with reason to believe that their political and financial ambitions would be stymied by our anti-corruption policy in Ukraine," Yovanovitch told lawmakers.
Trump referred to Yovanovitch as "bad news" in the July 25 phone call with Ukrainian President Volodymyr Zelensky that led to a whistleblower complaint from a US intelligence official. The US president added that Yovanovitch was "going to go through some things."
The phone call and complaint were the primary catalysts for the impeachment inquiry, which has gathered further evidence of a broad effort to pressure Ukraine into launching investigations that would help Trump's reelection campaign.
The White House released a summary or partial transcript of the July 25 call.
Yovanovitch in her public testimony offered an impassioned account of what it felt like to read the summary and learn that Trump had smeared her in a conversation with a foreign leader.
"It was a terrible moment," she told the House Intelligence Committee. "A person who saw me actually reading the transcript said that the color drained from my face. I think I even had a physical reaction. I think, you know, even now, words kind of fail me."
Describing how it felt to read the summary, Yovanovitch said she was shocked, appalled, and devastated "that the president of the United States would talk about any ambassador like that to a foreign head of state — and it was me. I mean, I couldn't believe it."
Yovanovitch said Trump's comments on her to Zelensky made her feel threatened.
As Yovanovitch testified, Trump went after her on Twitter: "Everywhere Marie Yovanovitch went turned bad. She started off in Somalia, how did that go? Then fast forward to Ukraine..."
Yovanovitch, who over her career has spent years on overseas assignments as a foreign service officer, was asked about Trump's tweet in real-time during the hearing, and she said it was "very intimidating."
House Democrats subsequently accused Trump of witness intimidation.
Yovanovitch in her testimony also decried State Department leadership for not doing more to stop US foreign policy from being hijacked. She said department leadership did not do enough "to push back as foreign and corrupt interests apparently hijacked our Ukraine policy."
And she was dismayed that department's leadership did not do more to defend her as she faced public attacks, including from the president's eldest son, Donald Trump Jr.
"Our Ukraine policy has been thrown into disarray, and shady interests ... have learned how little it takes to remove an American ambassador who does not give them what they want," Yovanovitch told lawmakers.