When Germany invaded Poland in September 1939, it gained control of about 2 million Jews in the occupied territory. The rest of Poland was occupied by the Soviet Union, which had control of the rest of Poland's pre-war population of 3.3–3.5 million Jews.[141] German plans for Poland included expelling gentile Poles from large areas, confining Jews, and settling Germans on the emptied lands.[142] The Germans initiated a policy of sending Jews from all territories they had recently annexed (Austria, Czechoslovakia, and western Poland) to the central section of Poland, which they called the General Government. There, the Jews were concentrated in ghettos in major cities,[143] chosen for their railway lines to facilitate later deportation.[144] Food supplies were restricted, public hygiene was difficult, and the inhabitants were often subjected to forced labor.[145] In the work camps and ghettos, at least half a million Jews died of starvation, disease, and poor living conditions.[146] Jeremy Black writes that the ghettos were not intended, in 1939, as a step towards the extermination of the Jews. Instead, they were viewed as part of a policy of creating a territorial reservation to contain them.[147][l]
The little white house was located on the west side of the Birkenau camp, behind the Central Sauna which was completed in 1943, and near Krema IV. The Central Sauna got its name because this was the location of the iron chambers where the prisoners' clothing was disinfected with hot steam. The Central Sauna also contained a shower room with 50 shower heads.
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.[2][3]