Mengele identified himself as a Catholic. It is worth noting, therefore, that as Mengele began his research at the University of Frankfurt, Achille Ratti, 79--who had earned a triple doctorate in philosophy, theology, and law--was working in Rome. Ratti would die before World War II began, but in the relative quiet before that genocidal storm, he faced important decisions about his relationship to Nazi Germany. Ratti was better known as Pope Pius XI, leader of the Roman Catholic Church.

Pius XI and Josef Mengele never met. Nevertheless, the Pontiff knew about Mengele's Nazi masters and their devotion to "racial hygiene." From the beginning of Adolf Hitler's power, Pius XI had recognized two other realities as well. First, he understood that Nazism jeopardized the Catholic Church's authority. Second, he knew that Germany's Jews were besieged with difficulties. Pius XI's feelings about those matters coincided with the description that Winston Churchill offered on April 14, 1937: "We seem to be moving," Churchill said, "toward some hideous catastrophe."