The Nazis established the Racial Hygiene and Demographic Biology Research Unit ("Rassenhygienische und Bevölkerungsbiologische Forschungsstelle", Department L3 of the Reich Department of Health) in 1936. Headed by Robert Ritter and his assistant Eva Justin, this Unit was mandated to conduct an in-depth study of the "Gypsy question ("Zigeunerfrage")" and to provide data required for formulating a new Reich "Gypsy law." After extensive fieldwork in the spring of 1936, consisting of interviews and medical examinations to determine the racial classification of the Roma, the Unit decided that most Romani, whom they had concluded were not of "pure Gypsy blood," posed a danger to German racial purity and should be deported or eliminated. No decision was made regarding the remainder (about 10 percent of the total Romani population of Europe), primarily Sinti and Lalleri tribes living in Germany. Several suggestions were made. "Reichsführer-SS" Heinrich Himmler suggested deporting the Romani to a remote reservation, as had been done by the United States for its Native Americans, where "pure Gypsies" could continue their nomadic lifestyle unhindered. According to him: