“One of those lines of inquiry relates to people we suspect being involved in a paedophile ring,” head of the Homicide Squad, Detective Superintendent Michael Willing, said at a press conference on Friday.

“We are vigorously pursuing this line of inquiry,” he said.

"We have recent information that we have received that relates to a paedophile ring that may be operating," Superintendent Willing said.

"It's a ring operating in that area [near Kendall], we believe," he said.

Superintendent Willing said William's parents had shown incredible strength in coming forward in a public appeal for information.

On Thursday, William's parents gave their first public interview since the toddler vanished from the yard of his grandmother's home in Kendall on the state's Mid North Coast on September 12 last year.

"We've seen the tremendous pain they've been going through not knowing what has happened to William," Superintendent Willing said.

"They have laid bare their feelings in a heart-wrenching plea for the community's help and are doing everything in their power to seek the safe return of their little boy. 

"They need answers and that's why we are committed to finding out what has happened to William.

"If anyone has William please return him to a safe place."

William's mother said on Thursday she has a vision in her head that somebody "reached over and ... has gone 'clump' on his shoulders, picked him up and moved him on ... because ... that's the only way ... to explain for him not to be there".

The toddler's parents say they cannot live not knowing where he is or what has happened to him. 

"We need to know where he is and we need to know what happened to him ... 'cause we can't live forever ... like this," his mother said. "His sister can't grow up never knowing what happened to her brother."

William's mother says she always suspected her three-year-old was abducted and had not simply wandered off.

"If somebody has him and if he is alive ... I want him to be safe, I want him to be feeling loved and I want someone to be looking after him ... because to imagine that something else is going on ... we can't live a life like that," his mother said.

The plea from William's parents, who cannot be identified for legal reasons, comes ahead of a fresh appeal from police on Friday for information into William's disappearance. 

"I thought that immediately," his mother said. "I had a vision in my head, somebody ... I can't explain  it."

She said she was horrified that someone could just have taken her son. 

"You just can't take children ... he's three! He's three years old, he's only lived for three years, it's ridiculous ... he hasn't gone to school. He's reached none of those milestones that we all take for granted."

His mother's desperate plea to bring her baby home came after hundreds of police and volunteers failed to find any trace of the toddler within a 10-kilometre radius of his grandmother's home.

Homicide police are leading the investigation and believe the toddler was abducted in his favourite Spider-Man suit. 

In January, police raided the Bonny Hills home and Laurieton office of whitegoods repairman Bill Spedding after he was due to fix a washing machine at William's grandmother's home the week the boy disappeared. 

Police seized a laptop and mattress from Mr Spedding's office, excavated his front yard and drained a septic tank but have repeatedly said the businessman was not a suspect but a "person of interest". Mr Spedding has denied any involvement. 

Fairfax Media understands a three-day search of bushland in early March was instigated after a witness reported seeing a vehicle drive down a fire trail about the time William disappeared. The search zone was 21 kilometres from where the toddler disappeared. 

William Tyrrell and his family drive from Sydney's north shore to visit his grandmother's home at Kendall for the first time. William has a complicated family history and, for legal reasons, his family cannot be identified.

William, 3, was wearing his favourite Spider-Man suit and playing with his sister in the yard of his grandmother's home when he vanished without a trace about 10.30am.

Police, State Emergency Service, Rural Fire Service and hundreds of volunteers thoroughly search three-kilometre "hot zone"  around William's grandmother's home three times without finding a clue.  

A week after William vanished police widened their search to a 48-square kilometre area through the Middle Brother State Forest, looking for any signs of "human intervention" such as items discarded by a kidnapper in a car. 

Up to a dozen police and forensic officers raid a Laurieton unit occupied by "person of interest" Bill Spedding and seize a child's mattress and computer equipment which were sent off for forensic testing.

Police empty a septic tank and use an excavator during  a 48-hour search of the house where "person of interest" Bill Spedding lives with his wife  Margaret. 

Up to 30 police, including water police and dog squad officers conduct a three day search of thick bush and muddy tracks between Bonny Hills and Lake Cathie. Homicide detectives said a tip-off led them to believe they might find evidence in relation to William's disappearance.

smh.com.au