[user104658]

What really makes the whole thing so bizarre is that timeframe? We're talking literally minutes for her to vanish without anyone seeing or hearing anything - and we know there were people in the area within a few minutes walk in either direction - the time between her being seen further along and the phone being found on the bench is tiny. And there's nowhere for a vehicle for her to have been snatched that way... and it's a long way for someone to have carried either a non-conscious person, basically impossible to have dragged a conscious and struggling person.

Truly odd.

I think this must be why the police assume she has to have ended up in the river. There aren't many alternatives?