Yovanovitch was removed from her post in the spring by the administration, and has been cast by Democrats as an honorable public servant sacked for tying to do the right thing.
As BBG reminds us, Yovanovitch testified in private on Oct. 11 that she felt she was recalled following a "concerted campaign" by President Trump and Rudy Giuliani. Because she left Ukraine in May, she clearly doesn't have any direct knowledge of Trump's efforts to elicit a quid pro quo - or as the Dems are now calling it, a bribe.
Yovanovitch testified that she felt "threatened" by the way Trump spoke about her on the July 25 call, which is at the center of the impeachment issue. Trump called her "bad news" and said "she's going to go through some things."
Watch her testimony live below (it's set to begin at 9 am ET):