Can't kill them unless they are guilty of murder. Or in the paraphrased words of Johnney Cochran, " Since the wife did not die, he can not fry. "
Correct. The Supreme Court already covered this ground in a case called Furman vs. Georgia, back in 1973. Not only must the crime be first degree murder, but there must also be aggravating circumstances: killing of a prison guard while already serving life without parole, or killing the victim with great cruelty, or killing more than one victim. Otherwise, the Supreme Court has ruled the death penalty is cruel and unusual punishment.
There are already enough problems with the death penalty and it doesn't need to be extended to cases that do not involve the taking of a life. In my opinion, life without parole is severe enough. I'd have been severely annoyed if he got any less, but as far as outrage goes, it's really hard for me to get outraged about our legal system any more.
Let's face it. The victim can still lead a productive life, one that is worth living. She has a daughter and a new husband who love her. Executing her assailant sends an official message to her from the government: "We, as the representatives of the people of your state, are treating this exactly the same as a murder. Your life is not worth living and you would be better off dead."