UNKNOWN
There is a distinction in that a witch does not kill his own victim because he wants to be rich, whereas a ritual murderer, he kills a person because he wants to gain out of that.  In any case traditionally ritual murder was committed with the approval of traditional leaders, no commoner was allowed to kill another person.  We only find commoners now because of businesses, but otherwise in the past when there were no shops, ritual murder was secretly committed with the approval of a chief.