On Sunday, April 19, 1953, at 8:30-ish in the evening, Ronald H. Tammen, Jr., disappeared from his second-floor room in Fisher Hall on Miami University’s campus in Oxford, Ohio. He left everything behind — his wallet, his string bass, his car, his clothing, even his toothbrush. No one could figure out what happened to Tammen. Miami University officials were mystified, the Oxford PD outwitted, the FBI flummoxed. Since the spring of 2010, I’ve been conducting my own search for Tammen and what his disappearance might tell us about this enigmatic 19-year-old who landed himself squarely in the middle of one of the most bedeviling mysteries ever to hit the state of Ohio.