Well that's fucked up. Unfortunatly it's all too common when there's a death in the family, it brings out the worst in people when they see some easy $$$.
Almost that exact same thing happened when my grandfather got sick, I'd actually quit a job at the time and moved in with him to help him out because he absolutely refused to die in a group home or something (he was a stubborn old soldier). He had a few guns that he had promised me (that isn't why I was helping him), there was an old 1911, caliber which we got but there was a few old revolvers that were pretty nice, old authentic smith and wessons, colts and then a few older rifles.
Me and my dad wanted the guns because my dad had grown up with most of them and I'd even hunted when I was very young for deer in Michigan with a few of them.
Anyways I have a dead beat uncle who never showed up to visit my grandfather even though he lived like 30 minutes away, he showed up after my grandpa had died, I was out on a bike ride and he took all the guns and pawned them. The police wouldn't do anything because there was no official will and it was "family".
I talked to the pawn shop and the guns had already been sold but I learned that the uncle had sold them all for 700 dollars cash and the pawn shop owner also said the uncle had spent it all in the bar across the street hat day (small town, word gets around).
The funny thing is as we were cleaning out the house, we found a locked briefcase thing and my dad had found an unmarked key in the safe deposit box, well the key fit and there was 2 beautiful blued colt pythons and several boxes of "vintage" ammo for them.
There was even a note that said something like "roger" (my dad), I hope you found these because I don't want that asshole Wendell (uncle) to get them.
So we ended up with the old service 1911 that had been carried in ww2 and Korea and a few colt pythons but the guns that were pawned off for a big night of booze had a lot of sentimental value.
There was a lot of other stuff that that uncle stole but those guns chafed my ass the most. Flat out rude and disreapectful.