(CNN) Editors' note: This story, which originally published on October 10, has been updated with recent events in advance of Marie Yovanovitch's testimony Friday at an open impeachment inquiry hearing.

Ambassador Marie "Masha" Yovanovitch -- "someone who has never been hungry for the spotlight," as one former State Department official described her -- has increasingly found herself there as new developments in the Ukraine controversy have come to light.

The former top US diplomat in Ukraine is set to testify Friday at the second public hearing in House Democrats' impeachment investigation into President Donald Trump and Ukraine. In October, Yovanovitch defied the White House by testifying behind closed doors before the three House committees.

She told the investigators she felt threatened after the President used her name on a July 25 phone call with Ukrainian President Volodymyr Zelensky, according to a transcript of her testimony that was released earlier this month.

She has been maligned as "bad news" by Trump but is known as "one of the best" to her diplomatic peers.

Since being unexpectedly removed from her post in Kiev in May, Yovanovitch has become increasingly ensnared at the center of the widening scandal.

"I would imagine for her this is pretty much worse than her worst nightmare in that not only are you being publicly criticized and condemned by your head of state but also the idea of all of this public attention. She's a pretty reserved person," the former State Department official told CNN.

Trump personally ordered Yovanovitch's removal, according to The Wall Street Journal . She was accused without evidence by Rudy Giuliani -- a former New York mayor and Trump's personal attorney -- and others of trying to undermine the President and blocking efforts to investigate Democrats like former Vice President Joe Biden.

Trump has repeatedly disparaged Yovanovitch, including on his call with Zelensky.

"The former ambassador from the United States, the woman, was bad news and the people she was dealing with in the Ukraine were bad news so I just want to let you know that," Trump said to Zelensky, according to a rough White House transcript

In October, 10 Democratic senators called on Secretary of State Mike Pompeo not to impede her testimony -- and to come out and defend her.

"For months, Ambassador Yovanovitch faced political attacks based on disinformation and statements later proven to be false," the senators wrote in a letter to the top US diplomat. "Throughout these events, you have said nothing publicly in her defense. You have not made a single remark defending Ambassador Yovanovitch or heralding her more than three decades of service to the American people."

The diplomatic community has rallied behind Yovanovitch in the weeks since the contents of Trump's call were disclosed, and some former diplomats have also called for the State Department and Pompeo to lend their public support to the career foreign service officer.

Fiona Hill, Trump's former top Russia adviser, told impeachment investigators last month that she was "shocked" when she read Trump's comments about Yovanovitch in the rough transcript of his call with Zelensky, according to a transcript of her testimony

"Particularly on Ambassador Yovanovitch, and very saddened because, again, Ambassador Yovanovitch is a great American, and I don't think any American citizen should be disparaged by their President," Hill said. "So that made me very sad and very shocked and, yeah, not too happy."

Retired US Ambassador Nicholas Burns called for "the higher levels of the State Department" to "come out and defend her."

"They should say she was a good ambassador, she did what was asked. She did what her constitutional duty asked her to do, represent the United States ably and honorably," Burns told CNN. "She deserves an apology, a public apology."

Two major groups representing the diplomatic community issued statements in support of the diplomat, with the American Academy of Diplomacy stating that Trump's comments in his call with Zelensky were "deeply troubling."

The half dozen former State Department officials who spoke to CNN about the former ambassador to Ukraine all praised her skill and experience.

Yovanovitch was sworn in as ambassador to Ukraine in August 2016. Multiple former officials told CNN they thought she was an ideal choice to serve in Kyiv.

"Masha (Yovanovitch) knows that part of the world so well, speaks the languages, knows the issues cold," retired US Ambassador James Melville told CNN. "They couldn't have had a better ambassador than Masha."

Yovanovitch was strongly committed to US foreign policy objectives in Ukraine and outspoken in highlighting corruption there, according to numerous former officials.

"She understood that corruption was the 'Achilles heel,' so to speak, of Ukraine," a former State Department official who knows Yovanovitch told CNN. "And so Masha, by doubling down on corruption and making it kind of her leitmotif of her tenure as ambassador, was doing exactly what she should have been doing and what US policy has been in Ukraine for quite some time."

As a small child, she immigrated with her parents to the United States.

"They survived poverty, war and displacement, and finally arrived in the United States, with me in tow, in search of freedom, opportunity, dignity and accountability," she said in her 2016 Senate confirmation hearing.

Yovanovitch graduated with a degree in history and Russian studies from Princeton and has a master's degree from the National War College.

She joined the foreign service in 1986 and went on to serve in ambassadorships under three presidents.