Another thing. There is no evidence that she had arranged to get a lift from a colleague that morning.
No text messages to that effect anyway.
I suppose it possible that she may have arranged a lift verbally the previous afternoon whilst at work, but then I would have thought the police would have interviewed every colleague of hers known to have driven her to work previously (this, I believe, was what led police to a previous arrest in this case).
So if she was expecting a lift at around 0540 then it must surely have been with someone else, not working for the university? Who, therefore, knew her movements and knew she would be on early shifts that week - and could arrange a lift by means other than text messaging?
That last question seems pertinent given that she would appear to have avoided the Nags Head for several days prior and therefore could not have made any such arrangement face to face in the pub with anyone there, unless it was made the previous week (which seems unlikely). Unless someone dropped by her address? In which case, who?