Tall, masculine, and blessed with a matinee idol’s baritone voice, Robert Stack certainly looked every inch the movie star, but he actually found his greatest fame on television. His iron jaw and terse delivery made him the ideal crime fighter to tackle the worst gangsters of the Jazz Age on “The Untouchables” (ABC, 1959-1963). That air of moral inflexibility still carried freight almost 30 years later, when he hosted “Unsolved Mysteries” (NBC/CBS, 1987-2002). Prior to and between those two series, he co-starred in a number of popular films, earned an Academy Award nomination, and even got a