In total, this group included around 2.1 million people, and many of them were willing to share their information. The Volkspolizei also had around 173,000 "voluntary helpers." ...

Richard Bessel, Policing in East Germany in the wake of the Second World War, Crime, Histoire & Sociétés / Crime, History & Societies, Vol. 7, No. 2 (2003), pp. 5-21 ...