Wilkes interviewed everyone connected to the crime. Except Julie but he did interview Jeremy.
The book is factually correct. Unless you can prove otherwise.
I was the person authorized by Jeremy to provide Roger Wilkes with access to all the then available material for use in his book, we didn't have all the material at that time, that is available today. This was arranged as part of a package, where Roger Wilkes would pay for the cost of a provisional report from the New York ballistics and blood spatter expert, Herbert Leon McDonnell...
Nobody had any proof then, that additional silencers had been given to police by the relatives, if we didn't know, how could Wilkes have known - Wilkes book, is a factual historical account of what was known about, and could be proven at the time...