I want to thank everyone here for the interesting and civil discussion, the insight, the maps, etc!
I feel very sad this happened to this lovely young woman
Do you think she could have been raped and then taken her own life because of the rape? Though not likely that she'd have medication to do that with her and any other method would have shown up on the PM. Would hypothermia show up on a first PM?
We have discussed hypothermia in so many cases but, for the life of me, I can't remember if it can be determined conclusively upon autopsy? I'm thinking so but will defer to other posters' opinions.
ETA:
Not very clear cut...
http://www.ncbi.nlm.nih.gov/pubmed/976901
http://www.researchgate.net/publication/260371558_Postmortem_diagnosis_of_hypothermia
http://www.archivesofpathology.org/doi/pdf/10.1043/1543-2165(2006)130[1297:HAHMIO]2.0.CO;2
Since the autopsy did not show an obvious cause of death I believe there can only be two causes: hypothermia, or some kind of drug. I'm sure samples are being tested for drugs and toxins now. Only if/when they come back negative will the coroner turn to hypothermia as a probable cause of death.
Hypothermia does not leave any signs in a body, the determination is made by way of excluding all other causes and taking circumstances into consideration.
I think it is quite likely she died of hypothermia that night, it doesn't need to be freezing for it to occur.
My theory at the moment is that after the rape she might have been so freaked out that she just tried to get to the next major road to get help, or maybe to a hospital or doctor she knew? Is there a hospital in the area? She might have been confused and irrational, and maybe she was drunk as well, and walked aimlessly, scared. Is it possible she climbed over the wall down to the water to wash herself? Might she have passed out and lay in the cold, maybe even in the water (without drowning) and died from hypothermia? I can even see a scenario where she was so crushed by what just happened that she just sat there by/in the water, cold and shivering, but unable to get up and walk home, and just fell asleep at some point, and didn't wake up again. Possible?
Yes there does seem to be a big gap in CCTV between the Devonshire Cat and Napier Street which a car journey might explain.
The gap in time must have been when she was raped?