Thomas Riha vanished on March 15, 1969, sparking a mystery that lives on 50 years later. A native of Prague, Czechoslovakia, Riha was a popular teacher at the University of Colorado at Boulder and a handsome man, with thick, graying hair and a wry smile. After his disappearance, the FBI and the CIA told local law enforcement and university officials that Riha was alive and well and had left Boulder to get away from his wife. But, as Eileen...