The Sipo (Security Police) was a combined force made up of Gestapo and Kripo. It was founded in 1936 after Himmler was appointed Reichsführer-SS and Chief of the German Police. It was accountable to Hitler alone, so it had no connection whatsoever with justice or the law. In occupied Netherlands the Sipo fell under the Higher SS and Police Leader H.A. Rauter and maintained close links with the SD. Until 1943 the Security Police and the SD came under the command of W. Harster and his successor E. Naumann.

• J. Matthäus, ‘Sicherheitspolizei’, in: W. Benz, H. Graml en H. Weiß ed., Enzyklopädie  des Nationalsozialismus (München 1997) 729-730
• L. de Jong, Het Koninkrijk der Nederlanden in de Tweede Wereldoorlog Deel 4. Mei ’40 – Maart ’41 (Den Haag 1972) 266-268.
• L. de Jong, Het Koninkrijk der Nederlanden in de Tweede Wereldoorlog Deel 7. Mei ’43 – Juni ‘44 (Den Haag 1976) 520-521.