The two cars, which police say were kept secret for a year for tactical reasons, were parked across the road from Williams grandmothers house on Benaroon Drive with their divers side windows down.
She said she noticed the cars while she was playing with William in the garden that morning and realised after he had vanished that they too were gone.
I realised that night that William went missing that I had actually seen two cars, she said.
I raced down to the command van, because theyd set up a command centre in the backyard and I raced down there and said Id remembered the two cars and I described the cars to them and all that sort of thing.
Those cars were not here, they were not there when we were looking for him.
She said she believed there was a reason the owners of the cars had not come forward and identified themselves to police.
Either theyre involved, or theyve seen what happened. And we just need them to come forward and say this is what we saw., she said.