I've opened myself to the idea of the existence of ghosts, and been to places where other people said they experienced ghosts, but nothing. Zip. I think people really want to believe ghosts exist, but in the end there's no evidence for it. Most things that mediums ascribe to ghosts can be explained logically. I always wondered why ghosts would show themselves in reflective surfaces, or even shower curtains 'n stuff. It has no apparent logic behind it, no reason why ghosts would do that. Or why they'd feel the need to show themselves if they can't really converse with you. I think cases like that are similar to seeing Jesus's face in a sandwich. People just want to see things, and so they do. The mind's powerful like that, and we already know the mind's biologically programmed to see human shapes and faces.
Another problem is that nobody seems to know what ghosts are or what they can do. Everybody's got a different explanation and some people just make stuff up on the spot and decide ''yup, that's what ghosts do''. It's just not based on evidence, or even logical reasoning many times. Some people say ghosts can move things, others say they can't.
Mediums I've pretty much accepted are full of crap. Nobody has ever passed James Randi's (fair) challenge. If they're psychic, why the need to ask you questions (they should already know the answer) and expect a response to be able to continue? Cold reading and stuff like that has been debunked (or explained I should say) many many times.
On the question, not all serial killers lack empathy. Some just feel that they 'need to' kill. Others simply have negative emotions that overpower their 'positive' ones. Why, no idea. Some kind of chemical imbalance in the brain that causes it, perhaps? I'm no expert on these things. Just saying this whole debate about serial killers not ever being perturbed by the ghosts of their victims... useless. And if they were tormented by ghosts, you think they'd tell people? Or that the people they tell it to care? They're killers. Also, how do you ''develop a conscience''?'If you don't have one by the age of 20 or so, I don't think it's possible for you to 'obtain' one.
In the end nobody even knows if ghosts (if they even exist, for which there is no evidence nor anything that makes it likely) can show themselves to everyone. What if the killer is the only one who can see them? And why is it that ghosts are always seen? Why not just felt? All of this depends on human sight, which is extremely fallible.
I'm more interested in the idea that you can see parts of parallel universes, but then again, why would a few people be able to see it, and like 99,9 % of the earth's population can't? It's all a bit weird. And why would ghosts from parallel universes perhaps look exactly the same as dead relatives, or wear the same clothing style as that of the prime universe? But these are all questions, who knows, maybe it's possible.
