Theories about Parry from "In Cold Blood"

[The Reborn]

Hey everyone,

I am currently working on a big project about Truman Capote's "In Cold Blood". It's a project for school, and in it I am supposed to analyze the criminals Dick and Perry, mostly Perry with some theories from psychology. I was wondering if anyone in here knew about some very good theories to put on a guy who never killed a man before and then suddenly kills an entire family. Which theory could explain that. I'm already working on Albert Bandura and I would appreciate it if any of you had some texts to send me or link me to or some ideas what to write about.

Thank you very much..

Jesper Quistgaard, from Denmark

[jno]

Have a look at about page 20 here

http://books.google.co.uk/books?id=Cre7qsswRiw C&printsec=frontcover&dq=Inside+the+Minds+of+M ass+Murderers#PPA18,M1