I am not as certain as others about the SP conviction. I find it absolutely amazing that there was not a drop of blood on the boat or in the house or on any of his clothes. I get blood all over the place from cutting a finger--and her head and limbs are missing? No knife, no saw, no blood, no bone chips. An inch of hair with a root? Hair yanked with a comb can come out with the root.
Duct tape would be more incriminating than hair--and his "confession" to the girlfriend might be the most convicting yet.
Strangulation doesn't leave blood residue as a general rule. Not saying she was strangled but that would explain the lack of blood.