My war on Logic

This summer I read a little bit of the book called the "Zodiac". I read only the letter that were originally written by the Zodiac. There is a movie coming out soon that is based on the situation. I will say I do not know much about it except for what I read. However; I will say that the brief part that I read really weirded me out. If your not sure what I am talking about the Zodiac is in reference to the Zodiace killer. The letters in question that I mentioned above were the letters that the killer actually sent to the local papers. They involved a cipher of cryptic letters which supposedly would give his identity away. He also mentioned that there was a time where the police talked to him after a killing. He was walking down the street after one and the police stopped to talk to him and he pointed them in another direction. The really weird part of the letters is that the reason for his killings were that he was collecting slaves for the afterlife.
I guess its that part most of all that really weirds me out. I am not saying that a serial killer is not messed up enough. I guess the fact that he was playing with the cops obviously showed that he was a smart individual. However then the hole afterlife slave that really adds the fucked up piece to the whole things. This is coming up now because I am actually up doing a change for work and a movie called "The Zodiac" which is based on the killer is on cable. I am actually interested in seeing the version that comes out this spring. As it comes to serial killers based on what I know of them this one seemed to be the smartest and one of the most messed up of them. It really weirds me out to think that someone this clever was able to pull off this kind of horrible violence.
How does one differerenciate right from wrong if you already believe you are right? I am guess that this person believed they were doing good or the "Lords work" depending on the mentality. Just that alone really weirds me out. If I see the new movie I will let you know.
It gives me chills.