The death penalty for rape of an adult has ruled unconstitutional by the Supreme Court. You may be thinking of South Carolina, where they were trying to institute the death penalty for rape of a child 12 and under. The Supreme Court has not ruled whether such a law would be unconstitutional or not.
No, the talk radio guy up here in Boston -Howie Carr- went to school in NC in the late 60's/early 70's and said that was the law at the time ... or at least he thought so ... maybe it was the law back in the 1800's or early 1900's