WASHINGTON (AP) — A former Trump campaign aide appeared for hours before a federal grand jury Friday, after he defiantly insisted in a series of news interviews just days earlier that he intended to defy a subpoena in special counsel Robert Mueller's Russia investigation.

Sam Nunberg spent more than six hours inside the federal courthouse in Washington. He declined to speak with journalists on the way in or out of the building, and it was not immediately clear what testimony he offered to the grand jury or what documents he provided.

His appearance marked a turnabout from extraordinary public...