The perspective of a stalker/molester/killer in a crime story?

Try reading In Cold Blood by Truman Copote and Lolita by Vladimir Nabocov. The first is about two cold-blooded murderers and is based on a true story. The second is about a man obssessed with a young girl. These books should give you a better idea of how to write from the perspective of a stalker/molester/killer.