> Somebody knows you really well. They knew that you wouldn't likely be in that part of the house at that time. They knew your door was unlocked. They knew that something valuable was there. They knew how to get in and back out without beings seen by a neighbor. My guess is that it was someone you know, and maybe someone you trust and would never suspect.

I doubt that completely. It was an opportunist crime: they were walking past the back of the house, and thought "why not?" They came in, took the thing most likely to contain cash, and left. People don't *plan* to break into a house just to steal a small bag.