I think I would just notify the owner. I doubt that the cops will or can do anything based on heresay.

My pickup was broken into a week ago. Several thousand $ of tools stolen. Second time in less than 3 years. I called, they came out, filled out paperwork, gave me a case # for insurance purposes and sent me a form letter. No way they can get the goods back. Too many hock shops and flea markets in the Dallas/Fort Worth area. If they were found, I couldn't prove they were mine. I expect, to the cops, one fish also looks like another. I think I would notify the victim and give him the opportunity to fill the guys butt with birdshot or administer a well deserved ass whuppin.