Back when I was a high school principal, our house was broken into, and a good amount of things stolen: computers, computer games. Oh yeah...and a half-full bottle of Boodles as well as a half-full bottle of Tanqueray. Well, even an "ijit:" knows that when booze is stolen, especially half-bottles, you done got kids doin' the stealin'.
Now me being half-intelligent, I returned to my high school principal office and fired-up the computer. I cross-referenced three databases: attendance, driving permits and discipline. About 12 students were absent that day/time. About 8 or so had driving permits. Exactly 3 had all three: absence, a permit to drive and recent discipline. I knew that one would almost certainly would not have done this. I knew the other two just might.
Well, I knew what their tire tracks looked like, and I knew what their shoe prints looked like. So, next day, I stood in the dirt parking lot and waited for the two "gentlemen" to return to school. Durned if the tire tracks weren't identical. I waited for the to step outta their ride, and durned if their shoe prints (both) didn't match.
I detained both in my office, made a photocopy of their shoe soles, and held them for the police. I had the car impounded for trespass and requested that the police (as a safety measure for themselves) conduct an "inventory search". As soon as the police popped the trunk, they found half-full bottle of booze...the kids were 17. Now it weren't my booze, it was booze stolen from their place of employment. The police immediately close the car and got a warrant.
Now, I never got my items back, but thank goodness it was insured...as I recall about $8,000.00 of items. This was in 1991, so that was some serious coin! They did try to steal the vault...couldn't. My point, it helps to know the day/time they broke in. Schools and other institutions create a daily supply of what we call "institutional memory". When you know the day and time of the event, you can begin a process of elimination.
Observations & Suggestions:
Who the Hades leaves a handgun out where it can be seen, let a lone stolen. I know, I had left my own M94 Winchester .30-30 when my house was broken into. Get the danged thing locked-up! Get rid of the glass vault and get yourself a real vault. They are not that expensive. Get yourself a small security system. There are some good and inexpensive ones available.
Sorry for your loss, but glad nobody was injured. Guns can be replaced, but lives can't!
Geno