With the Nazi occupation of Poland in September 1939, Werdyger was subject to frequent arrests and forced labor on the streets of Kraków. In the summer of 1940, when the Nazis ordered all Jews to leave the city, Werdyger's family moved to an uncle's home in Proszowice. In response to rumors of a mass deportation, David, his unmarried sister Yettie, and his parents went into hiding with 16 others in a bunker in their uncle's warehouse, where they were cared for by a Polish employee. Three weeks later, they sneaked into the Podgórze ghetto of Kraków. From there, his parents bought their way out of the ghetto into Sosnowice, where one of their married daughters was living. David never saw them again.