She's the career diplomat Rudy Giuliani sought to have removed as U.S. ambassador to Ukraine, and who the president himself has called "bad news." And on Friday she arrived to testify to House committees in the escalating impeachment probe against Donald Trump. Marie Yovanovitch, who was abruptly recalled from her post in Ukraine in May, was set give a deposition to congressional investigators probing Trump's dealings with Ukraine - despite a pledge from the White House to stonewall the congressional impeachment probe. Her testimony behind closed doors is among the first of several key depositions sought by House Democrats, who are investigating whether Trump pressured Ukrainian president Volodymyr Zelenskiy to investigate former Vice President Joe Biden. Lawmakers on Friday are expected to ask Yovanovitch about what she knew about efforts by Giuliani and Trump to push Ukraine to investigate Biden and his son. Giuliani has alleged she blocked those efforts. On Thursday, two of Giuliani's associates were arrested in what New York federal prosecutors said was a scheme to illegally funnel money to a pro-Trump election committee. Lev Parnas, a Ukrainian-American businessman, and Igor Fruman, who are mentioned in the whistleblower complaint that sparked the impeachment probe, are also accused by prosecutors of acting on behalf of Ukrainian officials and using their political connections to get Yovanovitch recalled. Earlier this week, the Trump administration blocked another key witness from testifying, U.S. ambassador to the European Union, Gordon Sondland. But his lawyers now say he will come back to testify before the House committees next Thursday.