William disappeared from the yard of his foster grandmother's home in Benaroon Drive, Kendall on September 12, 2014.

He hasn't been seen since.

The Deputy State Coroner overseeing the coronial inquest into the suspected death of William Tyrrell, Harriet Grahame, has released new photos of William taken by his foster mother on the morning he vanished.

She also released a full transcript of an interview by Detective Sergeant Laura Beacroft and Detective Senior Constable Louise Rodden of Strike Force Rosann with Ronald Chapman on April 4, 2017.

Mr Chapman was questioned extensively about his daily routine and what he saw the day William vanished, by counsel assisting the coroner Gerard Craddock, when the coronial inquest travelled to Taree for its second hearing in August.

Mr Chapman told Det Sgt Beacroft during an interview that he had heard a noise he thought would have been the postie.

When he went outside to investigate, Mr Chapman saw a vehicle with a child in the backseat, up against the passenger side back window and his recollection was the child was wearing a Spiderman outfit.

"I walked up the hall, I opened the front door, and walked out on to the front veranda, put my hand on the rail to walk down the steps and this vehicle had come around the corner and I wasn't paying much attention until I heard gravel run, from running down the bank into the, into the drain," Mr Chapman said in his statement.

"The car was very close to being in the drain. And that's when, um, I saw William in the back seat of a four-wheel drive with his two hands up on the window in his Spiderman suit, unrestrained. And under my breath I called the woman a stupid B."

Mr Champan said he recalled the woman was in her late 20s to 30s, of fair appearance, not very tall and "plump-ish". He said she had blonde hair combed up into a bun on top of her head. The car he recalled was an older style beige or brown box-shaped four-wheel drive.

He said the car was followed by another blue Ford sedan with tinted windows driven by a man, but could not say whether they were travelling together.

Read more: 'I recognised the boy': neighbour saw William being driven away, inquest told

Mr Chapman told officers before this, he was out in his backyard tending to his chickens. He said he would have returned back inside his home at about 10.15am. He said he heard the cars he described at about 10.45am.

The last photos taken of William by his foster mother are time-stamped between 9.35am and 9.37am on the morning he disappeared.

Det Sgt Beacroft told the inquest she didn't believe Ronald Chapman had made up what he'd seen from outside his Laurel Street home the morning of September 12.

Neither car has been identified during the investigation.

Read more: William taken by a "sneaky, complex person"

"I definitely saw William. I'm 100 per cent sure it was William in the back of the car. No doubt," Mr Chapman told the inquest.

Mr Chapman realised the significance of what he had seen when he saw a news story about William's disappearance that evening, he said.

"I recognised the boy's face and features," he said.

When asked by Mr Craddock SC if he thought he saw William Tyrrell, Mr Chapman said: "I did, yes."

The inquest had previously heard that William vanished about 10.15am, with a possible 10-minute window either side.

The retiree did not tell police about what he saw because he had heard on the news that officers would be doorknocking all residents within a one-kilometre range of the Benaroon Drive address from which William disappeared.

When that did not happen, he said, his sisters encouraged him to report what he had seen to police.

Read more: Foster and biological parents speak at opening of inquest into William Tyrrell's disappearance

Mr Chapman's account is the only credible sighting of William since he disappeared without a trace.

Anyone with information is urged to contact police.

"Investigators from the homicide squad's Strike Force Rosann are continuing to conduct inquiries, as they acknowledge the fifth anniversary of the disappearance of William Tyrrell today," homicide squad head Detective Superintendent Scott Cook said.

"The investigation remains open, and a team of investigators is continuing to explore lines of inquiry and persons of interest during the coronial process."

More than 15,000 pieces of evidence have been collected over the five-year investigation. A $1 million reward remains in place for information leading to the return or recovery of William.

Information suggests someone in the community knows something and police are still appealing for anyone with information to come forward and contact Crime Stoppers on 1800 333 000 or the solicitors assisting the Coroner on 02 8346 1388.

The coronial inquest will resume in March 2020.