Don't really think so, I just think he is speculating as we all are to a degree.That blows Clarke's credibility out of the water then. Mr "I think they expect to find 2 or more bodies here"
But we do know there are other missing children and CB has been questioned in relation to at least two of them. From what I know quite often murderers use the same deposition sites, maybe that is assumed to apply even to suspects.