I grew up with this kid who murdered his best friend last year. They'd gotten into an argument and be stabbed him to death, then called 911 and admitted immediately what had happened. He was always pretty shy, but really funny and good company once you got to know him. And he was genuinely a good person. I think he just snapped in that moment. He's apparently been nothing but remorseful since it happened.

And my uncle! While not an actual murderer, but rather, an attempted murderer. He took a little hatchet to his drug dealer's head and robbed him. Drug dealer miraculously survived, though. My uncle was always cold and his whole vibe was off. I think he's the definition of a psychopath.