Sex crimes detectives have joined the investigation into the disappearance of three-year-old William Tyrell, who vanished from his NSW mid-north coast home last week in what police now fear may be an abduction.
More than 30 investigators are working on the case and hundreds of people continued to scour the small town of Kendall and nearby bushland for a fifth day on Tuesday.
Superintendent Paul Fehon said it remained unclear whether William, who was last seen wearing a Spider-Man suit, had wandered off of his own accord or whether something more sinister had occurred.
Strike Force Rossann has been formed to investigate the disappearance. It's understood this includes the State Crime Command's Sex Crimes Squad and specially trained investigators who are experienced in the unexplained disappearances of young children.
The investigation has been widened to include the possibility that someone came in and out of the area.
"We are appealing for anyone who saw any people or vehicles in the vicinity of Benaroon Drive or in the Kendall township on Friday to contact police," Superintendent Fehon said.
"We are not ruling out any possibilities, investigators are exploring every possible avenue of inquiry."
Superintendent Fehon said that police sniffer dogs and cadaver dogs had failed to pick up any scent of William, fuelling fears he may not have wandered from the home in Benaroon Drive.
"We would have hoped to have found something by now," he said on Channel Seven on Tuesday.
"Whilst we still have any chance of survival, we will continue searching, but at the same time our investigative efforts, we're bolstering them to ensure that if anything has happened to William apart from him disappearing of his own means, that we come up with the right result."
Superintendent Fehon said the search on Tuesday would focus on a three-kilometre area around William's grandmother's house, while searchers would also return to the dams and waterways that had previously been searched over the weekend.
"There are hundreds of people on the ground who are searching for William, as well as resources on land and in the air, on horseback, trail bikes and 4WD and we still haven't found him yet," he said.
William had been playing in the front yard of his grandmother's house with his young sister when he disappeared at 10.30am on Friday.
"He was playing in the [front] yard, running around the house with his sister and in a short period of time both his grandmother and mother have noticed that he went missing. There is absolutely nothing further, but we're going to continue to comb over the area to try and come up with something," Superintendent Fehon said.
Family friend Nicole, speaking on behalf of William's parents, said William's family were enduring a fifth agonising day with no news of their little boy.
She described William as a "happy, cheeky, adventurous" boy who "loved everything to do with Spider-Man", fire engines and police cars.
"What we want to do is show him this on his 21st [birthday] and tell him that a lot of people came together to find him and show him all the police cars that were here for him," Nicole said.
Nicole said William had not been known to wander away on his own before. His parents were "devastated", and his sister knew her brother was "lost", Nicole said.
"She knows that there are lots of people looking for him and she wants him back, as the family want him back. She misses him, she misses playing with him," Nicole said.
"The family are just amazed that a community that doesn't know this gorgeous little boy have actually come together, all of the police, the SES [State Emergency Service], it's just incredible. They are beyond words with gratitude for everyone that every day has maintained hope, has continued to be persistent, has gone out looking for William."
Anyone with information about William's disappearance has been urged to contact Crime Stoppers on 1800 333 000.
