Nice one coneten. Miami seems to make sense as their proximity to salt water would predicate a stainless weapon.
With that being said my research on Miami PD guns seems to indicate that Tubbs carried a blue j frame model 38 snub and Crocketts' Bren Ten was stainless.
I think we can eliminate it being a vice squad weapon and it probably was carried by a patrolman.
Coneten you have a nose for locating those PD marked smiths. I still regret not getting that Ky State police 1940's era m & p. I think a retired trooper ended up with it if memory serves. Take care Brother.