geelongcate:
One thing that puzzles me is how the police can distinguish between an accident in which she ended up in the water, and an attack in which she ended up in the water. I get that an abduction is fairly unlikely because of the difficulty in getting her away from that location without being seen, but an assault in which she fell in the water during the struggle surely wouldn't look all that different to an accident. At any rate, for her to leave her phone behind means that whatever happened must have been quite sudden and unexpected.
The police/coroner look for defence injuries, under the fingernails. They can tell if someone has been punched or hit with something. If she has had an accident and tumbled in and she has been in the water all this time, it will be harder for them to know how she died, but if she hit her head on the way down, they will know. This happened to my sister who disappeared on a dog walk. The exact details of how she ended up in a river are unknown to this day - did she fall, was she pushed, did she come upon someone? We will never know and I hope Nikki's parents don't have to live with that, but I fear that they will.