Updated at 3:50 p.m. ET
Four witnesses are testifying in front of the House Intelligence Committee on Tuesday, starting the second week of public hearings in the ongoing impeachment inquiry investigation.
The morning session features Jennifer Williams, a career State Department staffer detailed to work with Vice President Pence's staff, as well as Lt. Col. Alexander Vindman, the Ukraine specialist on the National Security Council. Former U.S. envoy to Ukraine Kurt Volker and former Russia director for the NSC Tim Morrison are testifying in the afternoon.