The toddler - who was last seen wearing a Spider-Man costume - went missing while playing on the verandah at his foster grandmother's home in Kendall, on the NSW mid-north coast, on September 12, 2014.
An inquest into his disappearance was reopened on Monday and has examined search efforts for the three-year-old as well as the possible involvement of the foster mother in disposing of his body.
William Tyrrell's foster mother has always denied involvement in his disappearance. (Dan Himbrechts/AAP PHOTOS)
She allegedly loaded the boy's remains into her own mother's grey Mazda and concealed it before calling triple zero out of fear another child under her care would be taken away, Lidcombe Coroners Court was previously told.
The woman, who cannot be identified, has always denied any involvement in his disappearance.
The inquest will head into a final day of evidence on Thursday, when footage of the foster mother being questioned for four hours by the NSW Crime Commission in November 2021 is due to be played.
In this round of evidence - the fifth in the long-running inquest - coroner Harriet Grahame has heard from police officers involved in the search for William and an analyst who identified possible persons of interest.
A truck driver who was in the area when William disappeared spoke of the cars he saw at the time but offered no new leads.
Testimony has also been given by experts in how rainfall and flooding can move human remains and the preservation or disintegration of bones in the environment.
No one has been charged over William's disappearance and a $1 million reward for information stands.
A decade-long investigation has involved hundreds of persons of interest and dozens of searches.
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