As the senior State Department official in charge of Ukraine, George P. Kent was so alarmed by what he viewed as U.S. President Trump’s efforts to initiate “politically motivated prosecutions” there that he wrote a memo about it over the summer — weeks before an anonymous whistle-blower’s explosive complaint prompted the impeachment inquiry.
Ukraine-U.S. Relations
New York Times: George Kent, official who described Trump’s actions as ‘wrong for the rule of law’

US Deputy Assistant Secretary of State George Kent(C) arrives for a closed-door deposition in front of the House Intelligence, Foreign Affairs and Oversight committees on Capitol Hill in Washington D.C., on Oct. 15, 2019 as part of the Trump impeachment inquiry.