NOT good news.
But if it was a stick on nail and it was found in the bathroom (am I right in thinking a trashcan?) it is possible the nail still had a bit of sticky on the back.
If he picked it up off of the floor, something could have stuck. My, oh my, anything in that trash can could have stuck to residual sticky.
I would ask if she was fighting to breathe and the nail came off, was there any blood on the nail? (Although the sticky on those nails wouldn't be enough to draw blood)
Why didn't the other nails have the same material on them if she was clawing at somebody with them?
This is such a nightmare.