Evil serial killers

Original language is angielski.

"To kill is one of the greatest crimes against humanity--to kill repeatedly, accompanied usually by sexually motivated acts that are also taboo, is beyond human comprehension. Why do these people do it? What motivates them? Wildly deviant behaviour can sometimes be 'undrestood' when it is displayed by a lone madman, but what about the killers who are judged normal, or those who act in despicable a...