Once Dick and Perry are in the house they tie up the clutters and Perry kills them one by one after they could not find the safe, bullet in the head for everyone, most people would say Perry would be the most responsible for the murder because he pulled the trigger, but have you ever tried to impress someone you look up to by doing something you would not have done other wise?
Perry also looked at Dick as the provider, the father of their relationship. Even Capote Mentions the difference of the two. Dick is cold hearted and more matured as Perry is the kid of the two. If your parents tell you to do something most people would do it without question and that is one of many reasons why i believe that Perry should not be responsible for the murders.
Dick is most responsible for the murders of the Clutters, because had everything planned out, but made Perry do all of the dirty work, and of course he did it to impress Dick. Between obtaining the information, taking the initiative to follow through with his plan that he made to leave no witnesses, there was only one thing left to do for Perry and that was to pull the trigger. Dick is most responsible for the murders of the Clutters. Just because you did the dirty work that someone higher up has told you to do does not mean that you are responsible