LOS ANGELES - Entering middle age, Chico Brown lives in the world of children. He greets them at school, settles their fights, listens to their problems, watches them finish their homework, coaches their basketball teams, offers them rides home, reads their letters. He has four of his own children too, most of them nearly grown. But "they didn't know me," he says - for most of their lives, he was in prison. Now a gang-intervention specialist, dedicated to keeping kids from following his path, Brown was once a notorious drug dealer, an integral part of an operation that supplied much...