NPR's Scott Simon looks back at the tumultuous 1968 Democratic National Convention in Chicago, where violence on the streets reflected the division within the party during their nominating convention for president. Simon talks with Bill Daley, son of Chicago Mayor Richard J. Daley; Bill Jaconetti, who was a rookie police officer on the front lines during those tense days; Marilyn Katz, who was head of security for the protesting Students for a Democratic Society; and CBS News' Bob Schieffer, who was reporting from the convention floor.