You don't know that, .... neither do I ..... but I wouldn't rush to claim something that may be substantially more complicated than it appears to be.No i havent and i understand why you would think it would be different on a different day, however look at any of the police videos and go and look at the water above the weir - it isnt strong enough to move a body
So I'm putting the judgement of the "professional rivery/watery people", that were there on the spot at the time, above yours and mine.
It wouldn't surprise me that it also possible that an apparently looking still body of water may have strong under currents, or even exhibit some elements of laminar flow, my first google searches don't seem to throw anything up but I'll be interested to try more .... so I'll see what I can find ..