The diplomat was recalled from Kyiv as Rudy Giuliani - who is Trump's personal attorney and has no official role in the USA government - pressed Ukrainian officials to investigate baseless corruption allegations against Democrat Joe Biden and his son Hunter, who was involved with a gas company there.
The former US ambassador to Ukraine on Friday told a House of Representatives impeachment inquiry into President Donald Trump that Trump ousted her based on "unfounded and false claims" after she had come under attack by his personal lawyer Rudy Giuliani.
In the months leading up to Yovanovitch's removal, Trump lawyer Rudy Giuliani and his associates aided in an apparent campaign to have her recalled.
It had been unclear right up until Yovanovitch arrived whether she would appear because she still works for the State Department.
On Thursday, two foreign-born Florida businessmen who had helped Giuliani investigate Biden were arrested in what prosecutors said was a scheme to illegally funnel money to a pro-Trump election committee and other USA political candidates.
In one astonishing development, Giuliani was revealed to have dined with the two indicted men, Viktor Parnas and Igor Fruman, hours before they were arrested at Dulles airport with one-way tickets to Europe.
Last week, Sessions acknowledged meeting with the two businessmen. "He added that there had been a concerted campaign against me", Ms Yovanovitch said. "That is not unusual for you to meet people who then become contributors".
Marie Yovanovitch said she was "incredulous" at being dismissed by President Donald Trump in May.
Mr. Luskin said federal law and State Department regulations block his client from producing the materials.
According to Yovanovitch, she returned suddenly to the United States in the spring only to be informed by the deputy secretary of state that Trump had lost confidence in her ability to perform.
Mr Zelenskiy agreed with Mr Trump that she was a "bad ambassador" and agreed to investigate the Bidens.
Asked what Ukraine did to persuade the U.S.to release the aid, Zelenskiy said: "We have many diplomatic contacts".
Yovanivitch, who was sworn in as ambassador to Ukraine in August 2016, had served in ambassadorships under three administrations.
Her testimony could be a breakthrough for those seeking first-hand details about efforts by Trump, including through Giuliani, to pressure Ukraine to investigate Biden and his son. Multiple State Department officials have complained to TIME that Pompeo is failing to defend the professionals in the department he leads.
It appears to be some of these White House officials who first alerted the whistleblower who started off this process of what was going on with the July phone call and other matters related to Ukraine.
In her written deposition to Congress, Yovanovitch gave a description of the events surrounding her surprise removal from her post in Kyiv, weeks after having been told in March that the state department wanted her to extend her posting till 2020.
According to the whistleblower's complaint, some officials were concerned Mr Trump was soliciting interference from a foreign government for his own personal political interests during his call with President Zelensky. "She would not accept me as a new president well enough".
"In particular, her early recall raises questions about whether you put the personal interests of the president above the department's career personnel or United States foreign policy", they wrote.
As for Donald Trump, he spent Yovanovitch's time with Congress tweeting out as many compliments about himself as he could. The newly-elected Ukrainian president also insisted that he didn't talk to Trump about his decision to withhold hundreds of millions of dollars in military aid from Ukraine.
Yovanovitch did not respond to TIME's request for comment, and has shunned the news media as the Ukraine scandal has escalated.