That's a very good point. It is far more likely that it is someone else than either Holly or Shelley.
I don't think any of us are drawing conclusions. They'll get the identification done pretty quickly I imagine. They did not or would not release information on the description. Another paper said "extended" period of time.
http://www.wkrn.com/story/14595402/pedestrian-spots-body-in-cumberland-river
If at all in doubt they'll go the extra mile to be definitive over fast.