A sampling of Wilson’s concerns as she matured appears in the interstices of her exchanges with Otto Frank, which, remarkably, date from 1959 until his death, in 1980. For instance: “The year was 1968—etched in my mind. I can’t ever forget it. Otis Redding was ‘Sittin’ on the Dock of the Bay’ . . . while we hummed along to ‘Hey Jude’ by the Beatles.” “In 1973-74,” she reports, “I was wearing headbands, pukka-shell necklaces, and American Indian anything. Tattoos were a rage”—but enough. Tattoos were the rage, she neglects to recall, in Auschwitz; and of the Auschwitz survivor who was her patient correspondent for more than two decades, Wilson remarks, “Well, what choice did the poor man have? Whenever an attack of ‘I-can’t-take-this-any-longer’ would hit me, I’d put it all into lengthy diatribes to my distant guru, Otto Frank.”
Germany invaded the Soviet Union in June 1941. German propaganda portrayed the war against the Soviet Union as both an ideological war between German National Socialism and Jewish Bolshevism and a racial war between the Germans and the Jewish, Romani and Slavic Untermenschen ("sub-humans"). Local populations in some occupied Soviet territories actively participated in the killing of Jews and others, and helped identify and round up Jews. German involvement ranged from active instigation and involvement to general guidance. In Lithuania, Latvia, and western Ukraine, locals were deeply involved in the murder of Jews from the beginning of the German occupation. Some of these Latvian and Lithuanian units also participated in the murder of Jews in Belarus. In the south, Ukrainians killed about 24,000 Jews and some went to Poland to serve as concentration and death-camp guards. Military units from some countries allied to Germany also killed Jews. Romanian units were given orders to exterminate and wipe out Jews in areas they controlled. Ustaše militia in Croatia persecuted and murdered Jews, among others. Many of the killings were carried out in public, a change from previous practice.
The Nazis used the phrase Lebensunwertes Leben (life unworthy of life) in reference to the disabled and mentally ill. On 14 July 1933, the Law for the Prevention of Hereditarily Diseased Offspring (Gesetz zur Verhütung erbkranken Nachwuchses), the Sterilization Law, was passed, allowing for compulsory sterilization. The New York Times reported on 21 December that year: "400,000 Germans to be sterilized". There were 84,525 applications from doctors in the first year. The courts reached a decision in 64,499 of those cases; 56,244 were in favor of sterilization. Estimates for the number of involuntary sterilizations during the whole of the Third Reich range from 300,000 to 400,000.
Those who were not considered fit for work were taken immediately by truck from the Judenrampe to two make-shift gas chambers at Birkenau, which were located in two converted farm houses called "the little red house" and "the little white house." At least 75% of the Jews in each transport of 2,000 to 3,000 prisoners were deemed unfit for work and were destined for the gas chamber. The little red house, also known as Bunker 1, had a capacity of 800 people in two rooms and the little white house, called Bunker 2, had a capacity of 1,200 in four rooms.
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.