Choice - don't blame the murderer

First you have to realise that the brain is part if the body and that the bit that you call 'you' is not something that is driving your body - or that your body is a vessel for.

Every choice that you make is the final result of the entire history that has led up to it. If one thing in that history was different then the eventual choice would change.

This is because different experiences stimulate different brain developments and it is the brain structure and chemistry which culminate in the choices you make.

If I wanted to move my hand suddenly and unpredictably it wouldn't be unpredictable at all because I am doing so as a result of the situation leading up to it. 

If I were to choose not to move my hand in order to show I could make a different choice then that decision too is also the result of the situation that has evolved further. 

Take this further and it becomes clear that the people who commit crimes are not doing so out of choice. The fact that they do so is a result of the situation they are in so they can't be blamed for their actions. 

(They can of course be punished to dissuade them from doing so again).