I was thinking about this phraseology of DCI Redwood's recently. IMO it was a very cleverly thought out phrase.
It was given in the context of an interview in which Redwood was giving a very general sketch of the investigation so far and its aims, without giving away anything about what specifically he and his team were actually doing.
The phrase 'draw everything back to zero', upon analysis, is astonishingly ambiguous and vague. What is being drawn back to zero? What is 'everything'? What is zero? On what frame of reference, and where on that frame of reference does 'zero' appear? And who decides what and where? There really is no such thing as 'zero'.
Given that SY have given no undertakings that they will actually be able to solve this case, it would appear sensible to use a very broad brush in depicting the investigation. 'Back to zero' is just an umbrella term that implies a lot of work is being done without actually going in to what.No-one can question, analyse, or attempt to refute, because it's not clear what the parameters are.