A distant relative of mine decades ago did that exact same thing in Moline IL where he lived. When he died his daughter sold the gun to someone who went to register it in Michigan, but then the SHTF when it came up stolen and ballistics matched it to the former owners murder during a robbery way back when in IL.
Just be careful is all I'm saying, just like with a new girlfriend you really don't know where that thing has been and done before you got it.
If it's a decent piece, clean it very thouroghly and fire-lap the bore. Fire-lapping kits are still fairly cheap up at Brownells. Never deface a serial, though.
If it's junk, bury it deep someplace out of the way. No point in involving yourself in the inevitable s**tstorm.
Once you own it, never show it to anyone but your most trusted friend and never sell it.