The parents of missing toddler William Tyrrell have spoken of their heartache to 60 Minutes , as police hunt two cars that could be involved in his disappearance nearly one year ago.

William, then aged three, vanished from the front yard of his grandmother's home in Kendall, on NSW's Mid-North Coast, on September 12 last year.

He was wearing his favourite Spider-man costume at the time and has not been seen since.

William's parents hold his Spider-man toy. (9NEWS)

Police have revealed William's mother spotted two vehicles – a white station wagon and an older-style grey sedan – that were parked close together on the street where William's grandmother lived with their windows rolled down.

William's mother thought it was strange, but could have never thought it would become part of the investigation into the disappearance of her boy.

Police say they want to speak with the drivers of those cars.

The widespread investigation, headed by seasoned Homicide Squad Detective Inspector Gary Jubelin, has so far failed to find the missing boy.

"Every day I wake up and think 'this is going to be the day', whenever the phone rings I'm thinking this may be the breakthrough that we're looking for," Det. Insp. Jubelin said.

For the first time, it has also been revealed by NSW Police have executed search warrants that the public have not been made aware of.

Police also said that the number of people interviewed over William's disappearance was "in excess of 1000", with a "number of persons of interest".

60 Minutes journalist Michael Usher met William's parents - who cannot be named for legal reasons - speaking to the media for the first time since their boy disappeared.

William's mother went into great detail about the final moments she spent with her little boy on her mother's back deck before he vanished.

"I could still hear him, he was roaring, and then nothing," she said.

Missing toddler William Tyrrell. (Supplied) (Supplied)

"I couldn't see him, I couldn't hear him ... it was like the world came to a screaming halt.

"There was no wind, there were no birds, there was no movement there was nothing."

William's mother explains how she became frantic, racing around the house looking for her little boy who had vanished into thin air.

The triple-zero call William's mother made in the moments after captures the panic in her voice, a mother who knows her son would not wander off on his own.

By the end of that first day, 200 SES, police and local residents gathered in a desperate search for any sign of William.

It follows an interview with NSW Police released in April in which the couple pleaded for William's safe return.

The couple, who returned from that fateful holiday with a carload of William's toys, have recently removed his carrier from their car.

The Tyrrells and police investigating his disappearance are convinced William was taken by someone, in what was likely an opportunistic snatching.

"William was stolen. He was abducted, he was kidnapped, he was stolen, whichever word you want to use, somebody decided to take him," William's mother told 60 Minutes .

Det. Insp. Jubelin does not believe someone walked onto William's grandmother's property, but rather that William walked down the hill near the curb and was abducted by someone "with a propensity to commit an evil act like this".

Detective Inspector Gary Jubelin is leading the case into William's disappearance. (9NEWS)

"That's what we call an opportunistic situation, an opportunistic crime," he said.

He said it was clearly a dead-end street and that William's abductor would not be here by chance, and that they would be there "for a reason".

When William went missing he was wearing a two-piece Spider-man suit, which police hope will play a part in tracking him down.

Det. Insp. Jubelin recounted a recent sighting - corroborated by three different members of the public - which had him all but certain it was William.

Children no longer play alone in public, knowing someone in their midst might be the same person who took William.

Police are investing the possibility a pedophile ring was involved in his disappearance. (Supplied) (Supplied)

Authorities moved to quash rumours that William's disappearance was linked to the suppression of his parents' identity, saying the two are in no way linked.

Police maintain someone in the general public knows something about William's whereabouts.

"If you've got any doubts, you look at someone and you've got suspicion, pass that suspicion onto police," Det. Insp. Jubelin said.

"If you're protecting someone that you think is involved in this, you're as bad as the person involved in it."