I think the most obvious POI/scenario is what took place in removing little William from his life.
Spedding may have had plans to attend the award ceremony with Margret, but either dropped her there, or arranged to meet her there - the small window of opportunity I think allows Margaret to believe in her husbands innocents or enables her to turn a blind eye with less guilt.
Spedding arrives on Benaroon drive, & comes across little William & as we all have imagined, the scenario of "hey Spidey" takes place, William is whisked away in the heat of the moment, when Spedding realises that an opportunity to act on the side of him he has been suppressing in his day to day life (with individuals he could be directly linked to) has just come bouncing down the hill dressed as Spiderman.
What takes place next is anyones guess, I don't think, given the timeframe involved (Spedding needs to be able to convince Margret of his innocence by not extending his absence) that Spedding's urges to assault William ever had the chance to be inflicted on the young boy, William, being a boy "who knew his limits" realises he is no longer in the safe reach of his parents & panics, which triggers an asthma attack, Spedding also panics & instead of getting help, does nothing & the attack ends William's life.
Spedding either leaves little William in his van, (maybe in some sort of white goods packaging) or he brazenly removes the child's body & hides it in the pawn shop office. He goes about his activities with Margret, creating a partial alibi & sealing the deal for Margret to cover the holes in the rest of his alibi.
William is disposed of later, whether in Dunbogan, or on rout to or from, I'm not sure.
I think the fact that he did not technically assault William (as per my opinion), his guilt his less (not that pedophiles are usually the guilt ridden, ready to put their hands up type). He is able to calmly recite a script during a YouTube video stating over & over that he did not hurt William Tyrrell.
