Not nearly as bad as some stories here (had an otherwise mundane upbringing in central CT), but it involves my uncle, who died of brain cancer several years ago.
He lived at home all his life, and he was always a nice guy, though a bit slow (75ish IQ). He probably could've lived separately as he was able to drive and hold down work, but for whatever reason he didn't. Anyways, my grandmother died about 9 months before him from a stroke, and my grandfather a year or year and a half afterwards of old age type stuff. He was always nice to me and my siblings growing up, he taught me how to whittle and always had good beef jerky whenever we'd visit.
As such, my parents were cleaning out the house that was now empty, to put it up for sale, since my mother is the only surviving relative. They were a bit of pack rats, and my grandparents travelled quite a bit when my grandfather first retired (and apparently went with the souvenir buying approach of "quantity over quality"), so there was a fair amount of stuff to sort through. Well, apparently my uncle went a bit off the deep-end towards the end of his cancer (prior to being bed ridden at the very end) and became incredibly paranoid about black helicopters and the UN/New World order type of stuff. It didn't help that he lived in New Britain, CT, which was (and still is) a shit-hole, and there were police helicopters, newscopters and medivac helicopters flying within earshot.
So, my parents found about 25 guns of various types, sizes and quality stashed around the house. Sometimes under furniture, next to studs in the unfinished basement, etc, like he was preparing for an armed intrusion by international ninja assassins. No safetys, no chains, just lying somewhere stashed, just enough out of sight, but could be found with a wee bit of effort. He never owned a gun prior to the last few months, and the registrations showed they were purchased in a small time period. They also found thousands of rounds of ammo hidden as well. On top of that, apparently he was soliciting the companionship of a cheap Puerto Rican prostitute, who, we found out had stolen a number of handguns from him, as they turned up during a robbery/shooting in Hartford several months after his death (the serial #s were intact and the guns were registered to him).
It was all pieced together in the following months after my grandfather died, since first there was the hoard my parents found (which had already been destroyed by a friend of a friend in another police department by the time of the robbery/shooting), then the police calling about the guns used in the crime. The cops filled in the details about the prostitute, and my mother recalled my uncle's weird conversations when she would visit. Thankfully my uncle never took any action himself, but it was sad that was the final chapter for an otherwise decent and good man's life.
