We drive with Jubelin to the scene of the abduction — it is his seventh or eighth trip there. Each time he stays for an hour or so, usually alone, ­wandering up and down the street, trying to think like a paedophile, ­trying to get into the perpetrator’s mind. “You have to put yourself in that dark, murky world,” he says. “You have to swim in the swamp.”

Like Superintendent Paul Fehon, Jubelin was at first perplexed about how an offender could abduct a child from such a location. “I’ve got my paedophile hat on,” he says as we turn right into Benaroon Drive and motor slowly up the street. “I can’t reconcile that I can jump out of the car, run up and grab the kid, run back down to the car, put him in the car, and speed off.”

And then, he says, on his third visit, he remembered something. Years ago, he was driving one night to the house where his kids were living — like many homicide detectives, he’s been through a divorce. “The neighbour had twins, who were toddlers, and one of them was on the road,” he says. “I nearly ran over the child. I jumped out and picked up the kid and was ­carrying him in when the neighbours ran out and said, ‘Thank God’.”

It got him thinking. What if William’s case was not a planned abduction? “You’ve got to have two worlds collide — the situation where a three-year-old is momentarily unsupervised, and comes in contact with someone who is motivated to abduct that child … it doesn’t ­necessarily have to be this monster dressed in black who runs up, grabs the child and speeds off.” What if the person who abducted William had a reason to be in the street that day and had no malicious intent when he turned up Benaroon Drive?

We stop the car down the street a bit from William’s grandmother’s house. “You are here,” he says as we look up through trees to the house, “and you see a three-year-old kid in a Spider-Man suit on the road and there’s no one else around. What do you do?” It’s pretty easy to establish a rapport with a little boy. G’day Spider-Man. How are you going? Where’s your mum?

The way Jubelin sees it, you open the door and you put him in the car. Perhaps your first thought is to return him to his parents. Certainly, if anyone saw you now, you could say you were driving him to the police station in Laurieton, 15 minutes away. Instead of knocking on doors, you head back out past the showground. No one ­follows you. You cross the Camden Haven River and nobody notices young William with the seatbelt over him. You bypass the police station in Laurieton and you just keep driving. By the time William’s mother calls 000 you are 30km away. There are tens of thousands of hectares of dense bushland between you and Kendall. ­William is strapped in beside you, dressed in his Spider-Man suit.