The markings look similar to those on the rusty tide of guns Century Arms bought from the Puerto Rico police a couple of years ago. Most wound up at Sportsman's Warehouse stores across the country. They were mostly evidence guns (hence the case numbers) but some old duty guns, too. The evidence guns had been haphazardly stored in a warehouse which got soaked and battered during one hurricane or another. Rust abounded. Some were pretty good, though.
I bought a bunch of them - a 3" Model 13, a 2" Model 12, a snub 66, a Ruger Police Service Six, a couple of Beretta 92s, a 5906 and a 6906, and some others I've forgotten about. The prices ranged from pretty low to ridiculously high. They all sold eventually, though.
I bet the OP's gun is one of those.