They have no witnesses. They have no case. With this blunt observation, Mariann Colby--an attractive, church-going Shaker Heights, Ohio, mother and housewife--bet a defense psychiatrist that she would not be convicted of murder. A lack of witnesses was not the only problem that would confront the State of Ohio in 1966, which would seek to prosecute her for shooting to death Cremer Young Jr., her son's nine-year-old playmate: Colby had deftly...