For more than nine hours one Thursday last month, Gordon Sondland, the Trump administration’s ambassador to the European Union, spoke with U.S. congressional investigators as part of their impeachment inquiry focused on the president’s push to get Ukraine tied up in U.S. electoral politics.

Sondland was one of the “three amigos”—with Rick Perry, the U.S. energy secretary, and Kurt Volker, the former special envoy for Ukraine—participating in the Trump plan to pressure Ukraine to investigate Joe Biden and his son Hunter.