I have a very relevant comment to add.
I interned for a federal judge when I was a law student. One day I got to witness him sentence a serial killer to life in prison. The defendant took his wife to the Grand Canyon, and when no one was looking, pushed her over the edge. He got away with it for decades, because there were no witnesses and obviously no forensic evidence suggesting a homicide. But a persistent detective in Colorado learned one day after many years that the defendant was diagnosed with cancer, and drove to his house on a whim that he might get a quasi-deathbed confession. He was right. The bastard confessed. He was deemed a serial killer because this was one of, I believe, 5 different deaths he was implicated in.
That was the first day in my life that I'd ever made eye contact with a serial killer. I looked at him for a second and he looked at me. This sounds like a cliche but it's just a fact: there was nothing behind those eyes whatsoever. His soul was dead.
I did say "first day in my life" on purpose. I have the dubious distinction of being able to say that he was not the only serial killer I've met, because I fight bad guys in court for a living and have met at least one other, plus a mass killer here and there. I do not have a boring job. Sorry to digress.
"Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passions, they cannot alter the state of facts and evidence." --John Adams