Homicide cops join search for Tyrell

Homicide detectives have joined the search for little William Tyrell, who vanished from his grandmother's home on the NSW mid-north coast in early September.

Police are not treating the three-year-old's disappearance as a murder, but homicide squad officers are involved to "ensure a thorough investigation", a spokesman told AAP on Sunday.

"We have no evidence to suggest a particular scenario at this stage," he said.

Authorities and volunteers scoured bushland and waterways around Kendall, south of Port Macquarie, for weeks after William, wearing his Spider-Man suit, went missing.

They also searched the 21 houses in the estate where William disappeared while playing with his sister in his grandmother's backyard on September 12.

Police have sifted through hundreds of pieces of information that poured into Crime Stoppers, but have no solid lead.

About a week into the search, local police said they didn't think William would have survived in bushland, but they remain open-minded about what might have happened to him.

"We are completely open to any possibility, including human intervention," Superintendent Paul Fehon said at the time.

"If that has occurred, somebody knows something."

Sex crimes squad officers and other specialist police are also involved in the investigation.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000