His first run-in came in the mid-1990s, when he joined the Senate Whitewater Committee as a deputy special counsel. There he dug into allegations that the Clintons took part in a fraud connected to a Arkansas real estate venture gone bust. No charges were ever brought against either Clinton, but the scandal would eventually lead to independent counsel Kenneth Starr's probe that would result in the Lewinsky scandal.

http://www.cnn.com/2016/07/07/politics/who-is-james-comey-fbi-director-things-to-know/