I agree the pistol was originally manufactured in 1927-8 for the Rif Contract, undelivered to them, and subsequently issued to the Schutzpolizei in about 1929. The lack of a sear or mag safety indicates it was issued to a barracked
Bereitshaftspolizei unit that was subsequently transferred to the military in 1934-5. The police property marking was probably scrubbed at that point.
As stated by others, there are a number of threads which discuss the "Rif" or "sneak" pistols. I suggest you read
http://luger.gunboards.com/showthrea...TE-1920s/page7, especially post # 68.