He was certainly sick enough. I thought the man was 30 ish.Here's an "outside the square" thought. Is there a crazy chance Derek Percy and his father could have been complicit in this crime? It could account for the entirely different ages of the men allegedly witnessed near the children.. Could DP (aged 17.6) have been Jane's "boyfriend at the beach" and his father the mid-forties man seen playing with the children and asking about lost money? This could account for similar looks but confusing witness accounts regarding the ages of the suspect.
A really important aspect here is to note that DP's psychological profile as a killer has been deemed a real 'one-off'' and shows a forensic scatter pattern not matched anywhere else in the world. Part of this pattern must surely be genetic. DP was one of Australia's sickest criminals. Surely his traits didn't come from nowhere? Percy's own mother said the family "destroyed a lot of things" after Percy was arrested. A son and father acting together ticks a lot of boxes. We have no idea of the horrors and learned behaviours which may have taken place in the Percy household.
If it could be proven this nasty family were nearby at the time, we could have some answers.