Let's clarify something here. There is a DISTINCT difference between medical insanity and legal insanity. This guy could be crazy as a loon (and probably is, although it's MUCH scarier to think that he's not) and still fit the definition of legal sanity.
Legal sanity only requires that the perpetrator understand the difference between right and wrong at the time the crime is committed. So what if the guy is crackers? That's not the issue in a courtroom.
IMO, his behavior after the crime, the dumping of the body, etc., indicates to me that he had a crystal-clear understanding that what he had done was wrong and that it was in his best interest to get rid of the evidence... thus, legally sane.
And, to address the original question, the death penalty is far less than what this scumbag deserves. If there is a hell (which I don't believe in), I hope he spends his eternity being murdered over and over again in exactly the same fashion as his victim... and I'm not even sure that would be justice enough
