Or...
CSI: Yeah, but look at the wounds. This guy was stabbed in the heart, both lungs, both kidneys, the spleen, the pancreas, and the knife was left sticking out of the back of his skull, between an impaled brain and a severed brain stem. Clearly sneak attack damage has been applied here, and judging from the severity of this I'd say it's at least ten d6 or more. We're looking for a high-level rogue, possibly with ranks in assassin or invisible blade. Or Xena. Could be Xena.