(CNN) The top State Department official overseeing US policy in Europe and Eurasia is the latest witness in the House Democrats' impeachment inquiry.

Ambassador Philip Reeker, the acting assistant secretary in the Bureau of European and Eurasian Affairs, is appearing Saturday before the House Intelligence, Oversight and Foreign Affairs committees. As has been the case for all the other State Department officials who have testified in the probe, Reeker was subpoenaed to appear, according to an official working on the impeachment inquiry.

Reeker's Saturday testimony comes as the House works to move forward expeditiously with its closed-door depositions as part of the impeachment inquiry . Testimonies were canceled this week on Thursday and Friday in light of Rep. Elijah Cummings' memorial and funeral

Reeker is well-regarded among those who know him, with multiple officials pointing to his smarts.

"He is one of the more creative and independent-minded people you will find in the State Department," a former State Department official who knows him told CNN. "He is a problem-solver."