Resistance movements also helped Jews. Sometimes, this aid was intended to help the Jews; often it was rendered in the context of the general anti-Nazi resistance. In Yugoslavia, Serbian partisans attacked a concentration camp near Nish in 1941, freeing a small number of Jews. On April 19, 1943, the Committee for Jewish Defense, aided by Christian railroad workers, attacked a Belgian transport leaving Malines for Auschwitz. Several hundred Jewish deportees escaped with the help of the Belgian resistance.
Before the war, Mengele had received doctorates in anthropology and medicine, and began a career as a researcher. He joined the Nazi Party in 1937 and the SS in 1938. He was assigned as a battalion medical officer at the start of World War II, then transferred to the Nazi concentration camps service in early 1943 and assigned to Auschwitz, where he saw the opportunity to conduct genetic research on human subjects. His subsequent experiments focused primarily on twins, with little regard for the health or safety of the victims.