A former Nazi concentration camp guard has been stripped of his American citizenship. A US judge ruled that Iwan Mandycz had served as an armed guard at the Poniatowa labor camp in Poland in 1943 and later at the Sachsenhausen concentration camp near Berlin. Mandycz had concealed his Nazi collaboration when he applied to immigrate to the United States in 1949. The lawsuit against Mandycz was brought by the Justice Department’s Nazi-hunting unit, the Office of Special Investigations. Mandycz may still appeal the ruling.