No it isn't. The reason is that it is not within that person's control. You are murdering someone that through the shaping of life became that way and now is punished for it. If the whole reason for killing those kinds people were to state the wrong in their actions and therefore punishing by death it would be the same in the case of killing out of self-defence. Let us say a kid is instructed to kill by his parents. The voice of the parents is what drives that kid to do it (eventually). Does that mean he must be punished now for being a murderer. Why state this case, for the reason of the voice of the parent in which is not his voice and also in the case of the adults who commit the crimes. There is a voice within that drives them to do it. In also not his voice because life circumstances just made him that way. Just like how you have your habits they have theirs. It just happens to be a more serious one, but the fundamental is the same. Surely it must be dealt with, but not with killing them. The reason you do not kill/rape a person is because of perhaps the morals you possess or you are afraid to get caught. Either way something not chosen, but given is holding you back. These people don't have that.