Thomas J. Dart, 46, has been Cook County Sheriff since December 2006. As sheriff of the second-largest county in the nation, Dart is responsible for running the Cook County Jail, among other duties. With more than 9,000 inmates, the jail is the single largest detention facility in the U.S. Dart, a former Assistant Cook County State's Attorney, Illinois state Senator and State Representative, holds a J.D. from Loyola University and a Bachelor's Degree in history and general social studies from Providence College. He and his wife, Patricia, reside in Chicago with their four children.