By the spring of 1942, the Nazis had established six killing centers (death camps) in Poland: Chelmno (Kulmhof), Belzec, Sobibor, Treblinka, Maidanek and Auschwitz. All were located near railway lines so that Jews could be easily transported daily. A vast system of camps (called Lagersystem) supported the death camps. The purpose of these camps varied: some were slave labor camps, some transit camps, others concentration camps and their subcamps, and still others the notorious death camps. Some camps combined all of these functions or a few of them. All the camps were intolerably brutal.
Czeslawa Kwoka, age 14, appears in a prisoner identity photo provided by the Auschwitz Museum, taken by Wilhelm Brasse while working in the photography department at Auschwitz, the Nazi-run death camp where some 1.5 million people, most of them Jewish, died during World War II. Czeslawa was a Polish Catholic girl, from Wolka Zlojecka, Poland, who was sent to Auschwitz with her mother in December of 1942. Within three months, both were dead. Photographer (and fellow prisoner) Brasse recalled photographing Czeslawa in a 2005 documentary: "She was so young and so terrified. The girl didn't understand why she was there and she couldn't understand what was being said to her. So this woman Kapo (a prisoner overseer) took a stick and beat her about the face. This German woman was just taking out her anger on the girl. Such a beautiful young girl, so innocent. She cried but she could do nothing. Before the photograph was taken, the girl dried her tears and the blood from the cut on her lip. To tell you the truth, I felt as if I was being hit myself but I couldn't interfere. It would have been fatal for me." #
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.