His grip on German society tightened and those who publicly objected to Nazi policies were often sentenced to hard labour in the rapidly expanding concentration camp system. Jews were subjected to further laws restricting their rights, but rising anti-Semitism in Europe wasn’t limited to Germany. In the UK, Oswald Mosley’s British Union of Fascists gained support from sections of the public and press, even filling the Royal Albert Hall in April.
Almost all Jews within areas occupied by the Germans were killed. There were 3,020,000 Jews in the Soviet Union in 1939, and the losses were 1–1.1 million. Around one million Jews were killed by the Einsatzgruppen in the occupied Soviet territories. Of Poland's 3.3 million Jews, about 90 percent were killed. Many more died in the ghettos of Poland before they could be deported. The death camps accounted for half the number of Jews killed; 80–90 percent of death-camp victims are estimated to have been Jews. At Auschwitz-Birkenau the Jewish death toll was 1.1 million; Treblinka 870,000–925,000; Bełżec 434,000–600,000; Chełmno 152,000–320,000; Sobibór 170,000–250,000; and Majdanek 79,000.
After the war, Dr. Josef Mengele worked on a farm under an assumed name for a few years, then escaped to South America; he was never put on trial as a war criminal. If he had been captured and put on trial, Dr. Gisella Perl was prepared to testify against him. Dr. Perl worked as a prison doctor under Dr. Mengele, and was a prisoner herself. According to the book "Mengele, the Complete Story," Dr. Perl claimed that a woman prisoner named Ibi had escaped the gas chamber six times by jumping off the truck that was taking the prisoners from the Judenrampe to the gas chambers; Dr. Mengele was enraged when he discovered that she had returned to the selection line.
In 1935, Mengele earned a PhD in anthropology from the University of Munich. In January 1937, he joined the Institute for Hereditary Biology and Racial Hygiene in Frankfurt, where he worked for Dr. Otmar Freiherr von Verschuer, a German geneticist with a particular interest in researching twins. As von Verschuer's assistant, Mengele focused on the genetic factors that result in a cleft lip and palate, or a cleft chin. His thesis on the subject earned him a cum laude doctorate in medicine (MD) from the University of Frankfurt in 1938. (Both of his degrees were revoked by the issuing universities in the 1960s.) In a letter of recommendation, von Verschuer praised Mengele's reliability and his ability to verbally present complex material in a clear manner. The American author Robert Jay Lifton notes that Mengele's published works were in keeping with the scientific mainstream of the time, and would probably have been viewed as valid scientific efforts even outside Nazi Germany.