I would agree with that only if the hair was not also attached to her head. If that was the case, I would have to think that the hair got entangled during her abduction and her possibly fighting off the perpetrator. Otherwise, as you stated, that hair could have been there as long as she wore the necklace. I remember finding bits of my hair entangled in a gold chain I wore and rarely took off.
Then we need to find out if testimony bears that out.