I dunno – his defense will be some sea creature dismembered her. Also those stab wounds were probably teeth puncture wounds from the same sea critter. That kind of argument.
I’m not saying that will work, but I could see a lawyer claiming that. How long were the torso and parts in the sea anyway? My guess is the thing that will hard to explain away will be saw marks on bones, if there are such on the torso and parts.