Hans Fleischhacker was a German anthropologist with the Ahnenerbe and a commander in the SS of Nazi Germany. He worked with Bruno Beger on some projects, making measurements of Jewish people. He was with Beger at Auschwitz when the people were selected to be part of the Jewish skeleton collection, a project of the Ahnenerbe. At their post-war trial, Beger was found guilty of full knowledge of the scope of that project, while Fleischhacker was found not to be aware that the purpose of the measurements was to select the 86 people to be murdered at Natzweiler-Struthof camp.
In 1940 he also joined both the Nazi Party and the Waffen-SS. Before long Fleischhacker saw service with the SS Race and Settlement Main Office. Following the invasion of Poland he was sent to Litzmannstadt as part of this group in order to perform measurements on ethnic Germans and determine whether they were suitable for resettlement programmes in the east or simply for forced labour. His main base of operations was at Łódź. In 1942 Fleischhacker was, along with Heinrich Rübel, chosen by Bruno Beger to work with him in an SS project to determine the racial type applicable to the Mountain Jews of the Caucasus, a group that did not readily fit the Nazi's existing ethnic paradigms. Fleischhacker was chosen for this task due to a thesis he was preparing at the time dealing with skin color amongst Jews. The following year he worked again with Beger, this time at Auschwitz concentration camp where again his duty was to measure physical features of the inmates in order to determine to which race they belonged. He took measurements of the persons selected for the Jewish skeleton collection, who were sent from Auschwitz to Natzweiler-Struthof concentration camp to be gassed.
Post-war trial and work
After the Second World War Fleischhacker was held in various internment camps until appearing before the board of arbitration in 1948, where he was designated Mitläufer - not a fully committed Nazi but one who nonetheless went along with Nazism. He was able to return to anthropological research at the Goethe University Frankfurt in November 1950 and subsequently worked as a researcher and lecturer at the University of El Salvador, then at the Tübingen Anthropology Institute and returned to the Goethe Institute in Frankfurt until 1968. Along with Beger and Wolf-Dietrich Wolff, Fleischhacker came under investigation for his time at Auschwitz. A case was not brought against the men until 1970, as their connection to the Jewish skeleton project was not known until then. Ultimately the case against him was dismissed the following year as there was insufficient evidence to prove that he knew he was involved in extermination and only Beger was convicted.