Truman Capote's novel In Cold Blood and an interview with him The Story Behind a Nonfiction Novel by George Plimpton both reveal that impulses, projections made from others such as Dick, and behavior with emotions are the origins of homicidal mentality.

Violent Impulses are a major cause of the homicidal mentality. All people have violent impulses as some time or another. For example, Perry repeatedly throughout the novel says he is going to kill Dick, and he said, "I almost did shoot him" (Capote 233). It is very common to hear non-criminals say, "I'd like to kill this person," but non-criminals often do not mean that they are going to, or even would, kill anyone. What Perry was doing, just as ordinary people would do, was simply acknowledging anger and frustration. All of us suffer from fear and feelings of helplessness. Most people can acknowledge feelings of rage, fear...