Reichsführer-SS Heinrich Himmler, head of the SS, approved the site in April 1940 on the recommendation of SS-Obersturmbannführer Rudolf Höss of the camps inspectorate. Höss oversaw the development of the camp and served as its first commandant. The first 30 prisoners arrived on 20 May 1940 from the Sachsenhausen camp. German "career criminals" ("Berufsverbrecher"), the men were known as "greens" ("Grünen") after the green triangles on their prison clothing. Brought to the camp as functionaries, this group did much to establish the sadism of early camp life, which was directed particularly at Polish inmates, until the political prisoners took over their roles. Bruno Brodniewitsch, the first prisoner (who was given serial number 1), became "Lagerältester" (camp elder). The others were given positions such as "kapo" and block supervisor.