Democrats running the impeachment inquiry have started releasing transcripts of closed-door testimony, which has taken place over the last month.

First up, they released the depositions of Marie Yovanovitch, the former US ambassador to Ukraine who was besmirched and who raised concerns about Rudy Giuliani's shadow foreign policy.

They also released testimony from Michael McKinley, a former ambassador and top aide to Secretary of State Mike Pompeo, who quit his job in protest when Pompeo and others would not stand up for Yovanovitch.

There were a number of details released in the depositions of Yovanovitch including how the former envoy told impeachment investigators that a Ukrainian official warned her in 2019 to "watch my back" because of Giuliani and his associates Lev Parnas and Igor Fruman.

Yovanovitch also said that she felt threatened by the US President's words after reading a transcript of the call between Trump and Ukraine President Volodymyr Zelensky. She also testified that when she asked for support over attacks from Giuliani and others, she was informed of a concern that Trump could undercut the State Department.

Read more on what the newly-disclosed transcripts revealed here.