POLICE records c1820 - 1875

hello list from Australia,
my query is - what type of Police records would be in Archives for the above dates ?
Johann Carl Ernst SCHRADER was a Police officer and Prison Guard in Osterode am harz from c1838 - till c1872 .- where might I find those records ?
O am H dont seem to know much about the Policeforce and / or a Prison . It is a long time to be in one place so I am hoping to locate more info .
Does anyone have some suggestions ? He was not born there and seems to have died elsewhere - unknown though at this stage.
Thanks for ANY assistance Yvonne Marshall nee Brachmann.