If you're forced to make the claim, and they drop you, then contact your state Attorney General first, then the local TV news. As a media person, I can safely say look at this guy gettin' a raw deal from The Man stories get play.
At the same time, get in touch with every local music store and pawn shop you can reach...on the off chance it wasn't an inside job, the thief will be looking to offload the bass for cash fast. Cash rewards tend to get results too.
I trust there's already a police report on file?