On May 19th, 1939, the S.S. St. Louis sailed from Hamburg, Germany to Havana, Cuba with 937 passengers; almost all of them were Jews escaping with their lives. This was one of the last ships that left Germany before the outbreak of World War II. Most of the passengers had applied for U.S. visas and were only planning on staying in Cuba until they could enter into the United States. The U.S. State Department in Washington, the U.S. consulate in Havana, and the owner of the St. Louis were aware that they might not be able to enter Cuba, but the passengers were never told.
From the very onset of war, Hitler and his inner circle, including Göring, Himmler, and Goebbels, contemplated what to do about removing the Jewish menace, or "the Jewish Question." The attack on Russia in June 1941 raised the level of intensity concerning this unresolved issue. On the Eastern Front, the future of the thousand-year Reich was clearly at stake. Hitler therefore adopted a more radicalized approach in his rule as Führer to put all of German society on a war footing and to squash all obstacles in the path of victory. At this time, Hitler also radicalized his outlook toward the Jews in favor of a "Final Solution of the Jewish Question," in which the war against Nazi Germany's external military enemies would be expanded to include the internal arch enemy scattered throughout Europe and Russia – the Jewish population.
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.