Systematic examinations of rescuers have actually shown a high degree of heterogeneity among individuals. Rescuers came from divergent social backgrounds, varied widely in terms of political and religious involvements, and displayed different levels of friendship and animosity toward Jews. None of these variables has turned out to be a reliable predictor of the sort of person who was more or less likely to rescue Jews.
In early 1942 the Nazis built killing centres at Treblinka, Sobibor, and Belzec in occupied Poland. The death camps were to be the essential instrument of the “final solution.” The Einsatzgruppen had traveled to kill their victims. With the killing centres, the process was reversed. The victims were taken by train, often in cattle cars, to their killers. The extermination camps became factories producing corpses, effectively and efficiently, at minimal physical and psychological cost to German personnel. Assisted by Ukrainian and Latvian collaborators and prisoners of war, a few Germans could kill tens of thousands of prisoners each month. At Chelmno, the first of the extermination camps, the Nazis used mobile gas vans. Elsewhere they built permanent gas chambers linked to the crematoria where bodies were burned. Carbon monoxide was the gas of choice at most camps. Zyklon-B, an especially lethal killing agent, was employed primarily at Auschwitz and later at Majdanek.
Inside the sealed-off ghettos, the Nazis reduced food rations to starvation level, an experience described by Sara Grossman, confined at age 21 in the Lodz ghetto: "I don't think anything hurts as much as hunger. You become wild. You are not responsible for what you say and what you do. You become an animal in the full meaning of the word. You prey on others. You will steal. That is what hunger does to us. It dehumanizes you. You're not a human being any more. Slowly, slowly the Germans were achieving their goal. I think they let us suffer from hunger, not because there was not enough food, but because this was their method of demoralizing us, of degrading us, of torturing us. These were their methods, and they implemented these methods scrupulously. Therefore we had very many, many deaths daily. Very many sick people for whom there was no medication, no help, no remedy. We just stayed there, and lay there, and the end was coming."
Its historical significance makes the term Final Solution the most important example of the ability of Nazi language to integrate potentially different if not divergent approaches towards the so-called Jewish question into a conceptual frame of reference that helped facilitate systematic mass murder and to hide the Third Reich's genocidal policies behind technocratic abstractions, thus providing legitimization for perpetrators and enabling bystanders to claim not to know what was going on. Despite its inherent problems, most notably in evoking the illusion of coordinated planning and systematic implementation, the term Final Solution remains crucial for recognizing the process character of the Holocaust as a key element in a broader history of state-sponsored mass murder during the Nazi era.

A major tool of the Nazis' propaganda assault was the weekly Nazi newspaper Der Stürmer (The Attacker). At the bottom of the front page of each issue, in bold letters, the paper proclaimed, "The Jews are our misfortune!" Der Stürmer also regularly featured cartoons of Jews in which they were caricatured as hooked-nosed and ape­like. The influence of the newspaper was far-reaching: by 1938 about a half million copies were distributed weekly.

German soldiers question Jews after the Warsaw Ghetto Uprising in 1943. In October 1940, the Germans began to concentrate Poland's population of over 3 million Jews into overcrowded ghettos. In the largest of these, the Warsaw Ghetto, thousands of Jews died due to rampant disease and starvation, even before the Nazis began their massive deportations from the ghetto to the Treblinka extermination camp. The Warsaw Ghetto Uprising -- the first urban mass rebellion against the Nazi occupation of Europe -- took place from April 19 until May 16 1943, and began after German troops and police entered the ghetto to deport its surviving inhabitants. It ended when the poorly-armed and supplied resistance was crushed by German troops. #

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]