That's infuriating, and frightening. The words I can think of for this POS can't be used here in this forum, but I'm outraged on your behalf. How tight is your neighborhood? Do you think any of your neighbors may have seen anything? Does your neighborhood have a Nextdoor.com site? There may have been other people that were hit as well, and you could pool information and/or locate possible witnesses.

Keep an eye on Craigslist and ebay for the piggy bank....and maybe even pawn shops. If you have a photo of the piggy bank, you can upload it and do an image search on Google.