Aside from the case @mangeons mentions above, I have a few others. A good friend’s mother killed his (abusive) father. More of an act of self- or child-defense, though, in my opinion. A co-worker’s son was mugged, beaten and in a coma for a long time before he eventually died from his injuries. And the eeriest one, my ex-husband’s childhood friend turned out to be a serial killer. He’d been in my house, and I’d met him several times, before we found this out.