One could argue 'til the cows come home as to whether or not capital punishment was a deterrent, though it would be very difficult to argue that, before it was abolished, there were actually more murders because of it!
The ultimate penalty also helps - if only a tiny bit - the relatives of the victim to come to terms with the horror of their loss.
The ultimate penalty also helps - if only a tiny bit - the relatives of the victim to come to terms with the horror of their loss.