Based on the frame numbering, I'm assuming that the film came from a factory loaded cassette.
Is there any chance the student popped the end off of the cassette before turning off the lights?
I suppose there is a chance, but she insists there was nothing different compared to how the previous rolls were processed. Also, the second roll in the tank was very slightly fogged so it wouldn't be just a single cassette at fault.
I thought I'd seen every way a film could be ruined many years ago but this is a new one to me. I'm stumped.