Police will continue to search thick bushland in relation to the disappearance of three-year-old William Tyrrell after receiving a "breakthrough" tip-off in the past fortnight.

Police confirmed late on Monday that bones found in the bushland belonged to a small animal.

The search is expected to last several days while up to 30 officers comb through thick overgrowth and muddy tracks between Bonny Hills and Lake Cathie on the state's mid north coast.

William was wearing a Spiderman suit and playing with his sister in the garden of his grandmother's Kendall home almost six months ago.

Homicide commander Superintendent Michael Willing said police were searching for evidence in relation to William's suspected abduction but were not digging for a body.

"This will not be the last search in regards to this investigation," Superintendent Willing said. "There is always that possibility [of finding a body] but we are searching for evidence at this point."

The head of the investigation, Detective Inspector Gary Jubelin, said the fresh information was received well after police searched the Bonny Hills home and Laurieton office of washing machine repairman Bill Spedding.

"The search is based on recent information we have received and where a few lines of inquiry has taken us. This is fresh information," Inspector Jubelin said.

"What that evidence is, and whether it goes as far as a body, we simply don't know. But it is not a search specifically for a grave site."

In January police used an excavator and drained a septic tank at Mr Spedding's semi-rural property in Wandoo Place.

They also searched Mr Spedding's pawnbroker business in the nearby town of Laurieton.

He has denied an involvement in William's disappearance and has the full support of two of his children.

"We fully support him. We know that he has had nothing to do with this," his daughter-in-law told Fairfax Media.

Police have stressed Mr Spedding is not a suspect, but  a person of interest.

"At the very highest he is a person of interest but he is not the only person of interest," Superintendent Willing said.

At the time his home was searched, Mr Spedding said the police search had been difficult for him and his family, and that he and his wife were on the verge of having nervous breakdowns.

He had visited the home of William's grandmother four days before the boy's disappearance after a request to repair a washing machine.

A close friend, Colin, said Mr Spedding did not return to the grandmother's house with a spare part for the washing machine on the day William went missing because he could not get in contact with her.

Anyone with information has been urged to contact Crime Stoppers on 1800 333 000.