Yes I know they have. There's a big difference between process being carried out satisfactorily and being carried out rigourously right from the start with a fully open mind and no assumptions being made.
Is this a criminal investigation? No, we believe she fell in the river by the bench.
Have you looked into CCTV? Yes
Have you searched the river? Yes
Have you contacted the drivers on Blackpool Lane? Yes
Are you looking at dashcam footage? Yes
Due process completed satisfactorily.
Have you searched upstream of the bench because the bench may be a red herring and if she fell in it may have been elsewhere? No. (It was SGI who did that later).
Have you searched the house opposite and the outbuildings? No because this isn't a criminal investigation and the owner wanted us to get a search warrant.
Etc. Big difference between doing things by the book correctly, and being a bit more creative in your thinking.