I am writing a novel set in the 20th century in which the wife of a major character is murdered at Auschwitz. She was living and hiding in Paris during the Nazi occupation, but she was caught in 1943 and imprisoned in Drancy (outside of Paris) and then taken to Auschwitz on one of the last convoys out of Drancy and killed. My character, an American who had been fighting with the French Resistance, returns to NYC after the war and starts to find out what happened to his wife.
Here are my questions: What organizations were involved in searching for Holocaust victims at this period (late 1940s)? When did it become widely known that Auschwitz was a death camp? Was HIAS active in searching for Jews rounded up and deported during the war? What about the Red Cross?