I have always kept a complete record book on every car that I've owned. And give it to the next owner if he/she want it. Even receipts from gas purchases.
Happened to me years ago. I was in my backyard doing yard work and needed something from the garage. I had left the overhead door open, someone driving by must have seen my lawn mower and helped them selfs to it.
I know how you feel VIOLATED. The police here were absolutely no help.