WASHINGTON (AP) — Lawmakers heard testimony Thursday from the former special U.S. envoy to Ukraine who has become a central figure in the unfolding impeachment inquiry against President Donald Trump. Kurt Volker, a once obscure diplomat, became the first witness in the impeachment investigation as he testified behind closed doors. Investigators planned to ask about any role he may have played in Trump’s efforts to press Ukrainian officials for damaging information about the son of former Vice President Joe Biden.