ICB pp. 224-254

pp. 239  Dick and Perry stay at the farm house because Dick is "too ashamed to face it."  The "it" is that he didn't actually have the perfect heist.  He wasn't as smart as he led on.  Later, Perry initiates the killings when he reacts to Dick's cowardice (not cutting Clutter's throat) and then sees himself crawling on the floor of Nancy's room, trying to find a young girl's silver dollar.kills Mr. Clutter.  "The shame.  The disgust" (244) Perry feels causes him to kill Mr. Clutter.  To kill out of shame--to take four lives is disgusting, but Dick and Perry's morals are so tattered that they can't prioritize their feelings and, sadly, feel they can't control their actions.  This is the difference in the moral and the criminal mind.