Former U.S. Ambassador to Ukraine Marie Yovanovitch is appearing before Congress on Friday to cap off the first week of public hearings in the impeachment inquiry into President Trump.

It follows the testimony earlier this week from U.S. chargé d'affaires in Ukraine Bill Taylor and Deputy Assistant Secretary of State for Europe George Kent.

Democrats have been moving quickly with their impeachment probe. Sparked by a whistleblower complaint, the investigation has centered on whether the president improperly used his office to pressure Ukranian President Voldomyr Zelensky into ordering investigations -- including into the family of 2020 contender Joe Biden -- that could have been politically beneficial to his reelection campaign in exchange for the release of about $400 million in military aid.

The following is a look back at Marie Yovanovitch's background and connection to the impeachment inquiry:

Marie Yovanovitch's career

Yovanovitch is a long-time diplomat who has served under six presidential administrations over 33 years. She told lawmakers she was dedicated to carrying out America's policies in an evenhanded way no matter who was in the White House.

"I have understood that oath, a commitment to serve on a strictly nonpartisan basis, to advance the foreign policy determined by the incumbent president, and to work at all times to strengthen our national security and promote our national interests," she said, according to a transcript of the deposition.

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A Princeton graduate who also had a Master's degree from National Defense University, Yovanovitch worked at U.S. embassies around the world, including in Kiev, Moscow, London, Ottowa and Mogadishu, according to her government biography.

She was also the dean of the School of Language Studies at the State Department's Foreign Service Institute, was the principal deputy assistant secretary for the Bureau of Eurasian Affairs and previously was in charge of handling issues in Nordic, Baltic and Central European countries for that office.

More recently, President Obama in 2016 nominated Yovanovitch for the post of ambassador to Ukraine, a job she held until President Trump called for her ouster earlier this year.

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Yovanovitch said in a statement to investigators that she was abruptly told this spring to depart Ukraine "on the next plane." She later was told the president had lost confidence in her and had been pressuring State Department officials for many months to remove her, she said.

The Trump administration and some Republican lawmakers have argued that Yovanovitch's removal from the job had nothing to do with Trump's moves to have the Bidens investigated. But, The Wall Street Journal reported in October that she was recalled from Kiev after months of complaints by Trump attorney Rudy Giuliani that she'd been "undermining him abroad and obstructing efforts to persuade" Ukrainian leaders to investigate the Bidens.

Yovanovitch's testimony

Democrats are expected to use Yovanovitch's testimony to back up the narrative they started building Wednesday with Kent and Taylor.

Speaking with lawmakers behind closed doors, Yovanovitch said Ukranian officials told her late last year that Giuliani, the former New York City mayor, and Yuri Lutsenko, Ukraine's head prosecutor, were working together, "and that they had plans, and that they were going to, you know, do things, including to me."

She continued, "Basically, it was people in the Ukrainian government who said that Mr. Lutsenko, the former prosecutor general, was in communication with Mayor Giuliani."

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Republicans, on the other hand, are likely to challenge Yovanovitch on her claims from her closed-door interview that she had not responded to an email from a Democratic congressional staffer about a "quite delicate" and "time-sensitive" issue immediately after the whistleblower complaint was filed but before it was made public.

Fox News reported last week that Yovanovitch had responded to the staffer, identified as Laurea Carey, with her personal email. A spokesperson for the House Foreign Affairs Committee's Democrats said the correspondence was innocuous.

Fox News' Andrew O'Reilly and Mke Emanuel contributed to this report.