They got one fingerprint off the deceased. Who's to say that the print on the duct tape didn't belong to her? Whenever I've read about the injuries to her face, the majority of the time they are referred to as superficial. It's only a couple of more recent articles where I've read that they are stabbing wounds. It's possible someone has assumed those wounds were knife wounds. I would think the original autopsy report would have reported them as stab wounds if they were.