Istvan was born to a Jewish family in the small agricultural city of Torokszentmiklos, about 65 miles from Budapest. Istvan worked for the Hungarian railroads during World War I, and afterwards earned a degree in pharmacology. In the 1920s Istvan married Barbara Nemeth and they settled in Torokszentmiklos. In 1929 the couple had a son, Janos.
1933-39: During the early 1930s, after the onset of the Depression, Istvan helped his father in the family's grain exporting business. In 1933 Istvan and Barbara divorced and their son Janos went to live in Szentes. In 1938 the Hungarian government, which was sympathetic to Nazi Germany, began enacting anti-Jewish laws.
1940-45: In 1940 the Hungarian army forcibly conscripted thousands of Jewish males into labor brigades. Istvan was exempted because pharmacists were needed. In 1941 Istvan married Helena Haas. Three years later, in March 1944, Germany occupied Hungary. Istvan and his family were arrested by Hungarian gendarmes and taken to a makeshift ghetto located at a sugar factory near Torokszentmiklos. From there they were deported, via the Strasshof camp in Austria, to the Lobau labor camp near Vienna.
Istvan, his wife, Helena, and his son, Janos, were liberated in Lobau by the Red Army in April 1945. After the war, they emigrated to the United States.