It is possible for a writer to reach bizarre or outlandish conclusions while also having insights that may genuinely be new. Fresh eyes will one day approach this case in a way or ways we all can't see.
I hope the book is genuine and not just someone or some individuals messing about. Genuinely fresh eyes and thoughts would be interesting.
Scotland Yard.
I should stress, I am not particularly blowing the trumpet of Scotland Yard as vastly superior to the PJ, here, much of whose own work (not all!) in the shelved enquiry I am, quite genuinely, in awe of (including, and especially, the work of the GNR dog-handlers who first looked for Madeleine).
But it is a well-established phenomenon of human psyche that when one set of eyes (no matter whose) have been foucussed on an intractable problem for an extended period of time, a fresh set of eyes (again, no matter whose) can look at the same problem and spot something the first examiners simply missed.
The phenomenon is well established and recognised in domestic, UK, policing where officers of one force have failed to crack a crime and officers of a different force will be asked to re-examine the same crime (with fresh eyes).