'Watts, 1956. Young women of easy virtue are being murdered and mutilated in especially repellent fashion. The police and the press pay little attention, as long as the victims are Negroes but when a young white woman is similarly killed, the powers that be demand action. Problem is that the powers that be have little entree to the neighborhood. Sounds like a case for Easy Rawlins - the unlicensed, unofficial and very off-the-books black detective. . . 'Los Angeles Times'Times, leaders and heroes change. . . It seems somehow fitting that Bill Clinton's favorite do-gooder is Easy Rawlins, a savvy, down-to-earth African-American private eye based in Los Angeles. In White Butterfly, good-time girls, corrupt politicians and other crime-novel fixtures are all in place. But Walter Mosley's writing hums with the particular rhythms and blues of the black American experience. What makes these books special is their vivid portrayal of life in the side streets where Philip Marlow seldom ventured. 'Time