It's a fair point. Just wondering if stats bear this out.

I feel it's still quite a big step to go from rape to murder. Is every rapist capable of murder?

I suppose I agree with you if it means rapists end up killing their victims due to the fear of execution. That is definitely not wanted...

But then there's different kinds of rape as well. Does a man who inflicts no violence but doesn't accept "no" half way through sex when both parties are extremely drunk deserve the same punishment as a man who beats a woman senseless whilst gang raping her?

Imo, no. And my second example seems like the type who would murder to get rid of evidence as opposed to the drunk, who most likely wouldn't.