Ford pardoned Nixon without an indictment, I believe.
Nixon was in fact charged by the House of Representatives.
Source:History Channel "This day in history" http://www.history.com/this-day-in-history/nixon-charged-with-first-of-three-articles-of-impeachment
The House Judiciary Committee (under Peter Rodino) voted for three articles of impeachment, but Nixon resigned before the full House of Representatives considered the articles.