Rudolf Reder a.k.a. Roman Robak (April 4, 1881 – October 6, 1977) was one of only two survivors of the Bełżec extermination camp. His testimony after the war became very well known. He submitted a deposition to the Main Commission for the Investigation of German Crimes in January 1946 in Kraków. In terms of the number of Polish Jews who perished in its gas chambers, Bełżec had the third highest death toll among the six Nazi death camps located in occupied Poland, estimated between 500,000 and 600,000 men, women and children. Only Auschwitz-Birkenau and Treblinka killed more people during the Holocaust.
The postwar testimony of Reder was of special significance. This is because Chaim Hirszman, the only other survivor of Bełżec, joined the new communist militia in Stalinist Poland shortly after the war and was himself murdered in March 1946 by anti-communist forces before he was able to give a full account of his camp experience.