Sorry to hear such a thing Ben. I can only imagine how violated you feel.
As Yak Angler said..it looks like somebody who knew what he was there for ..and where to get it.
What would make a "friend" or acquaintance treat you so badly? As FBH said, there is
one major thing that would make them do it!
When one has a serious drug addiction..they have no friends, loved ones or acquaintances.. their
only friend is drugs,.. and more drugs.
Cops said it must be a big guy..+ drugs..Start thinking along those lines, perhaps someone will pop up.
One further bit of advice which may possibly help. I normally pull the butt plate off my guns and put a slip of paper in there, which reads... " this gun belongs to Joe Doaks, who lives at 32 Elm st, Everytown, MO Phone (765) 365-9954"'
Of course I just used a bogus address, but use your own in your own guns. You may even add " if anyone but Joe Doaks brings this gun to you, chances are it's stolen".. If a gunsmith finds it a couple years later, who knows, he may call you or the cops?
Just remember to remove the slip if/when you transfer it. A couple years ago I gave a gun to my grandson. He later was surprised to find gramp's note in the gun..about 20 years after I had placed it in there..