She may have entered the water, splashed about and managed to get out on the opposite bank. It's about 5 metres wide, if that, at that point so possible.
So the police say they have searched the house but this morning Nicola's friend says they haven't because it's not a crime scene.
Who to believe? The police don't appear to have searched upstream, according to SGI, which SGI have now done, so they do sound like they're working on some pretty basic assumptions.
I think the police have assumed she fell in, treated it as an accident, and just gone through the motions regarding other possibilities.