"Knowledge of the crime only the suspect could know."
Had a thought on this. I think most of us have assumed this knowledge involves some detail that is not currently in the public domain, but that's not necessarily the case.
If we assume this "knowledge" comes from something CB confessed to HB, that would have been in 2008. It was supposedly at a festival which I believe was in the July of that year. The PJ files which we are so familiar with now hadn't been made public at that point, most were realeased in August 2008 I believe. So if CB mentioned something that wasn't common knowledge at that point in time, that could I suppose be reasonably described as something only the perpetrator could know. Ok, technically the police would have also known about it too, but I could understand why HCW might make that assertion given the likelihood CB could have obtained such information from them.
Taking the example of CB possibly describing something that happened during GM or MO's checks, much of the details behind those checks had not been reported in the Press. Things like GM using the toilet or MO stopping to look at the books on the shelf that are mentioned in their statements were probably not common knowledge back then.
Not that it makes a lot of difference. Just pointing out that this "knowledge of the crime" might be something we do now know about, but that wasn't known back when CB recounted it.
Could be something as simple as a birthmark she had in a certain place maybe, or something to do with her body, that only parents know about?