volker. he worked with sondland to get ukraine to investigate burisma, the energy company where joe biden's son, hunter, sat on the board. but volker said, at the time, he didn't see the biden connection. >> in hindsight, i now understand that others saw the idea of investigating possible corruption involving the ukrainian company burisma as equivalent to investigating former vice president biden. i saw them as very different. >> reporter: volker testified, bottom line, the investigations president trump wanted were not in the national interest of the united states. >> i don't think that raising 2016 elections or vice president biden or these -- these things i consider to be conspiracy theories that had been circulated by the ukrainians, particularly the former prosecutor general, are -- they're not things that we should be pursuing as part of our national security strategy with ukraine. >> mary bruce with us live on capitol hill. a very long day, mary. you were on the air with us all