How did we get here? A timeline of the Ukraine impeachment saga

The impeachment inquiry has moved quickly, with more than a dozen witnesses, nearly 2700 pages of testimony and, now, public hearings. But how did we get here? Lisa Desjardins and Yamiche Alcindor take a look back at key events in the Ukraine saga and the previously obscure U.S. officials who will play important roles in the upcoming hearings.