This episode's headline: Fighting Crime; Conversation. The guests include MAYOR WELLINGTON WEBB, Denver, Colorado; MAYOR SHARPE JAMES, Newark, New Jersey; CHIEF PHIL KEITH, Knoxville, Tennessee Police Department; CHIEF ELDRIN BELL, Atlanta, Georgia Police Department; MAYOR RITA MULLINS, Palatine, Illinois; KENNE FANT, Author, Alfred Nobel: A Biography; CORRESPONDENTS: KWAME HOLMAN; CHARLAYNE HUNTER-GAULT. Byline: In New York: ROBERT MacNeil; In Washington: JAMES LEHRER