The term originated in the early years of the Nazi power in Germany. Germany, as a federal state, had a myriad of local and centralised police agencies, which often were un-coordinated and had overlapping jurisdictions. Himmler's grand plan was to fully absorb all the police and security apparatus into the structure of the SS. As a result, the SS took command first of the Gestapo (itself developed from the Prussian Secret Police) and later of all the regular and criminal investigation police.
Eventually, the state security police were consolidated and placed under the central command of Reinhard Heydrich, already chief of the party Sicherheitsdienst (SD), and named Sicherheitspolizei. The idea was to fully identify the party agency (SD) with the state agency (Sipo). Most of the Sipo members were encouraged or volunteered to become members of the SS and many held a rank in both organisations. In practice, however, the Sipo and the SD frequently came into jurisdictional and operational conflict with each other, due in large part to the fact that the Gestapo and Kripo had many experienced, professional policemen and investigators, that considered the SD as an organisation of amateurs and often found the SD an incompetent agency.
In 1936, the state police agencies in Germany were statutorily divided into the Ordnungspolizei (regular or order police) and the Sicherheitspolizei (security police). The two police branches were commonly known as the Sipo (Kripo and Gestapo combined) and Orpo.
In 1939, with the founding of the Reichssicherheitshauptamt (RSHA), the Sicherheitspolizei as a functioning office ceased to exist. The term survived in common usage, however, and was most often used by local security force commanders who adopted the title Inspektor des Sicherheitspolizei und SD. Such personnel typically had command over all SD, Gestapo, Kripo, and Orpo units in their area of responsibility and performed duties far more extensive than those of a modern-day Chief of Police. The Inspectors of the Security Police answered to both the RSHA and to local SS and Police Leaders.
Die Einsatzgruppen in der besetzten Sowjetunion 1941/ 42. Die Tatigkeits- und Lageberichte des Chefs der Sicherheitspolizei und des SD.(Review)
Jun 22, 2001; Die Einsatzgruppen in der besetzten Sowjetunion 1941/42. Die Tatigkeits- und Lageberichte des Chefs der Sicherheitspolizei...