If you are in 28mm then I can see the following possibilities:
1.- use Westwind GH00034 east european politzi.
they can pass as german policemen.
2.- use WW1 jaeger (renegade, GreatWarMiniatures, foundry or Ironclad) alas they are armed.
3.- conversions; use jaeger heads with appropriate bodies.
[Preiser did produce some policemen in smaller scales -1:87 and I think 1:72/76. I do not know of their fate]