a justification to sterilize an estimated 500 Roma and Sinti individuals between 1933 and 1939. Methods of research The task of the Rassenhygienische und Bevolkerungsbiologische Forschungsstelle (), a division of the Kriminalpolizei (Criminal Police), was to identify and categorize all Roma and Sinti people in Germany according to racial standards. Ritter, heading this organization, had a team of other racial scientists including Eva Justin, Adolf Wurth, Sophie Ehrhardt, and Ruth Kellermann. By 1937, the Research Unit was working with the Central Office of Reich Security, and the Reich Ministry of Interior, to travel across Germany in units to register "full-blooded" and "mixed-race" Roma or Sinti. The units referenced church records to track individuals' genealogies. As some of Ritter's assistants spoke Romani, they would interrogate Roma individuals who could not provide paper proof of their racial identity. Anyone who balked was threatened with incarceration. Along with tracking genealogies, the units photographed their subjects, took blood samples, and made anthropometric measurements. Ritter wanted the data to prove that the Roma and Sinti populations were genetically pre-disposed to crime as a "lesser race". Ritter in post-Nazi Germany Despite the Denazification of Germany after World War II, Ritter was not required to take responsibility for his actions towards the Roma and Sinti population during Nazi rule. All investigations against Ritter were discontinued. Ritter was hired to teach criminal biology at the University of Tübingen from 1944 to 1946, and was later brought in by the Frankfurt Health Office as a pediatrician. He hired his former assistant, Eva Justin, to work with him as a psychologist. References Crowe, David M. (1994). A History of the Gypsies of Eastern Europe and Russia. New York: St. Martin's Press. Kenrick, Donald; Puxon, Grattan (2009). Gypsies Under the Swastika. University of Hertfordshire Press. Friedlander, Henry (1989). The Origins of Nazi Genocide: From Euthanasia to the Final Solution. Chapel Hill: University of North Carolina. Lewy, Guenter (1999). "Himmler and the 'Racially Pure Gypsies'". Journal of Contemporary History vol. 34, no. 2, pp. 201–214. Lewy, Guenter (2000). Nazi Persecution of the Gypsies. Oxford/New York: Oxford University Press. Milton, Sybil (1994). "Holocaust: The Gypsies", pp. 209–265. Genocide in the Twentieth Century, eds. William S. Parsons, Israel W. Charny, Samuel Totten. Garland Publishing. Tebbutt, Susan (1998). Sinti and Roma: Gypsies in German-Speaking Society and Literature. Berghahn Books. External links Dr. Robert Ritter: Racial Science And "Gypsies" Robert Ritter profile 1901 births German psychologists