William Tyrrell's foster father says he started searching "everywhere" when he got home from a business meeting in 2014 and his wife asked "Is William with you?"
"Why would he be with me?" the male carer replied.
The man, who cannot be identified, gave evidence at the NSW Coroners Court on Wednesday - day three of an inquest into the three-year-old's disappearance and suspected death on the NSW mid north coast.
He was in Kendall with his wife and their two foster children, visiting the woman's mother, when William vanished while wearing his beloved Spiderman costume on September 12.
The man said he drove to nearby Lakewood about 9am for a strong internet connection for a conference call and planned to be home around 10.30am.
The three-year-old was last seen wearing a Spider-Man suit in the garden of his foster grandmother's home. Source: AAP
He sent a text to his wife about that time to say he'd be home in five minutes.
The foster mother called police at 10.56am to report the missing boy, estimating he'd been gone since 10.30am.
Counsel assisting the coroner, Gerard Craddock SC, on Wednesday asked: "You didn't stop and have a conversation with her (the foster mother) about where she'd already searched, is there any reason for that?"
"I had assumed in the time that I got home, if she couldn't find him, that she'd already actually done the immediate area including inside and outside the house," he said.
"I knew it would probably be best for me to start to branch out."
He told the inquest the boy knew the sound of his voice and he was hoping to find him "quickly" if he came close.
He looked under houses, external fences, pits, drains and sheds.
"Everything, everywhere he might have gone," he said.
"There was method to my madness, if I can say that, searching the immediate areas where I knew he could potentially travel in a period of time."
Hearings for the William Tyrrell inquest started this week. Source: AAP
In a police interview on September 18, the foster father told an officer: "He never wanders. He's not a wanderer."
Multiple neighbours gave evidence on Tuesday that they saw the "hysterical" foster father running around, screaming the child's name.
"I'm sure if William had been around, he would have come to him," neighbour Sharelle Crabb told the inquest.
Her husband, Peter Crabb, said he "looked in places where a little boy might hide" including driving to a nearby swimming pool but there was "nothing, absolutely nothing".
"They (the foster parents) were shouting and screaming off their heads for William," Mr Crabb said, noting numerous others were "coming out of the woodwork" to help.
Mr Craddock on Monday said he expected the evidence would establish William "was taken".
