The three-year-old disappeared from outside his grandmother’s house in Kendall on the NSW mid-north coast on September 12, 2014.
On the fourth anniversary of his disappearance, NSW Police announced in a statement that an inquest before Deputy NSW Coroner Harriet Grahame has been proposed for next year.
"Her Honour has requested a brief of evidence, which will be provided by the year's end," it read.
"The brief will cover various aspects of the investigation, as determined by the Coroner.
"The inquest will be an opportunity to test information and evidence gathered by Strike Force Rosann and further the investigation.
"This is another step in ensuring answers are provided to William's loved ones."
Despite an extensive search, there has been no trace of William since his disappearance four years ago.
Last September, police launched a fresh search and issued a grim warning to anyone involved with his disappearance.
“Now is the time for you to come forward,” head of the investigation Det. Chief Insp. Gary Jubelin said in a statement to WHO.
“Now—before we come for you.”
The officer hopes the $1 million reward offered by the NSW government will provide motivation for someone who knows what happened to William to come forward.
“Someone knows what happened; they might not be the one who took him, but know who did, and they’re potentially concealing a criminal offence," he said.