It's a pretty easy home experiment. All you need is one goldfish, one ziplock bag of water, and a freezer.
Goldfishsicles do not suffer from melting the way kiwi-strawberry-speach ones do.
I agree, cops may not do anything, but I could annoy the heck out of the theives. Find out where they live, park outside their house. Send pictures and video to the newspaper, stuff like that.
...get shot.