Alvin Dewey from the Kansas Bureau of Investigation wants to be meticulous in conducting the investigation of the brutal murders of the Clutter family. He also has a personal stake because he knew the family. As the investigation gets underway, Dewey is involved in developing two different concepts about the person or people who committed the murders, along with their methods. As he wants to weigh both alternatives carefully so as to base his conclusions on the evidence, at first he does not commit to either one. Before long he decides that the second scenario is the best supported.

The first concept or scenario is that there was a single killer. In addition, it seems likely that this person knew at least one family member and was familiar with the home and the residents’ habits. One piece of likely evidence is the behavior of the family dog. In this scenario, the armed intruder would have forced the adults to tie up their children.

In the second scenario, there were two people. One may have been the killer, while the second was their accomplice. In this scenario, the accomplice would have subdued and tied up the victims. A version of this theory is that both people directly participated in the murders.

The ways the bodies were tied and positioned influences his opinion. Dewey cannot accept that Herb Clutter would have cooperated in subduing or restraining his own children. He is convinced that the father and his teenage son would have actively resisted. It therefore is more logical that a second intruder was involved.