On 1 December 1958, in a part of the prison complex in the market town of Ludwigsburg, Wurttemberg, West Germany, a special judicial investigation office was opened with the unwieldy title of Zentrale Stelle der Landesjustizverwaltungen zur Aufklärung national- sozialistischer Verbrechen (Central Office for State Justice Administration for the Elucidation of National Socialist War Crimes), abbreviated to ‘Z-Stelle’ (Central Office). The initial main task of this special office was to examine in detail the organization, operation, staff, and victims of the six Nazi extermination camps at Auschwitz-Birkenau, Majdanek, Chelmno, Belzec, Sobibor and Treblinka, tracing original documents and photographs, and locating eyewitnesses, especially survivors, who could testify at resulting criminal proceedings for war crimes and crimes against humanity before West German courts. In addition, the Central Office was responsible for coordinating the various criminal investigations conducted by local State Prosecutors, special police war crimes units and the Kriminalpolizei.
The first major investigation directed by the Central Office concerned the Aktion Reinhard extermination camps at Belzec, Sobibor and Treblinka in eastern Poland in which about 1.5 million Polish and foreign Jews were murdered in gas chambers and their corpses cremated on open air pyres. The investigation, begun in the autumn of 1959 and which lasted until the mid-1960s, benefitted from the coperation of the Inspector-General of the Israeli police in Tel Aviv who, in his capacity as the head of Interpol in Israel, coordinated the search in that country for survivors and witnesses.
High on the Central Office list of war criminals who had been active in the Aktion Reinhard extermination camps was Lorenz Hackenholt who, in 1942 as a 28-year-old SS-Scharführer had played a leading role in the construction of gas chambers in all three camps. Nothing had been heard of him since the latter days of the war when he had been
 Adelbert Ruckerl, ed., NS-Prozesse Nach 25 Jahren Strafverfolgung: Möglichkeiten - Grenzen - Ergebnisse (Karlsruhe, Verlag C. F. Muller, 1972), p. 21.
 Letter from Tuviah Friedman, Director of Documentation at the Institute of Documentation in Israel for the Investigation of Nazi War Crimes, Haifa, Israel, to Senior State Prosecutor Dr. Schuele, Director of the Ludwigsburg Central Office, dated 22 September 1959.