What happened before William Tyrrell vanished
William Tyrrell's biological father has wept in court as the inquest into his missing son opened in Sydney.
The father, who cannot be named, wept as he sat with his half-brother's arm around his shoulders in the courtroom.
Missing William's biological grandmother also wept as she heard Counsel Assisting the inquest, Gerard Craddock, SC, give a dramatic recreation of events on the morning William went missing.
The three-year-old was dressed as Spider-Man, climbing trees and "pretending to be a daddy tiger" on the morning of his disappearance in 2014, the NSW coroner was told this morning.
"We heard him roaring around the garden and then I thought, oh I haven't heard him, I better go check on him, and couldn't find him," his foster mother told a triple-zero operator on September 12.
She said the three-year-old boy was wearing a Spider-Man suit and she'd been searching the neighbouring properties and green bushland for any sign of red. The woman also told the operator she hadn't seen anyone suspicious in the area. The audio file was played on Monday at the first day of a Sydney inquest into William's disappearance and suspected death in the "sleepy village" of Kendall, on NSW's mid north coast.
Counsel assisting the coroner, Gerard Craddock SC, said William's foster grandmother - whose house the family were visiting - had noticed "it had become quiet, too quiet".
"There had been one load roar and then nothing," Mr Craddock said.
The biological and the foster families of William Tyrrell sat on opposite sides of the court which was also packed with supporters for both sides.
NSW Deputy State Coroner Harriet Grahame welcomed William Tyrrell's families and friends to the court, acknowledging that losing a child "must be one of the greatest pains of all".
On one side of the courtroom, the foster parents - who cannot be identified - sat after being accompanied into court by NSW Police Minister Troy Grant.
They looked grim as they heard the triple-0 call made by the foster mother played in court, and details of the search for William as it became obvious he was nowhere in sight.
The foster parents were with William at his foster grandmother's house on the morning the three-year-old vanished from the NSW Mid North Coast town of Kendall on September 12, 2014.
William's biological mother is due to give evidence later this week.
Paul Savage, the neighbour who helped in the search for William, is also due to give evidence.
William's disappearance sparked one of NSW's biggest manhunts for a missing child.
Strike Force Rosann was set up to investigate, but no trace of the boy has ever been found.
Deputy State Coroner Harriet Grahame will conduct the inquest at the Forensic Medicine and Coroner's Court Complex at Lidcombe, in western Sydney.
A massive brief of evidence, containing at least 15,000 items, will go before Ms Grahame.
The first of two weeks of hearings will explore William's foster and biological families, the period of time around the disappearance and early parts of the investigation.
Throughout the investigation, William was referred to "a little boy lost" but police soon came to suspect something more sinister happened and zeroed in on known paedophiles and criminals from nearby holiday towns.
But no one has been charged for the suspected abduction.
It is understood investigators hope the first week of hearings will show William did not wander into nearby bushland but was, instead, snatched by a predator.
In mid-2018 they conducted a large-scale search of bushland near the Kendall home to rule out misadventure and firm up their theory.
The closely-guarded persons of interest list, which ballooned to include hundreds of names over the years, has been whittled down for the inquest's second sitting in August.
Some names on that list have been previously released by police but sources say one so-far unidentified person will be watched closely when they are called in front of the inquest.
Counsel assisting Gerard Craddock SC will deliver his opening address at 10am on Monday.