Anna Baker was tending to strawberries on her Herons Creek property on the NSW mid-north coast in September 2014 when she heard a child scream out.

"(It was) not very long, it sounded like maybe he was hurt," Ms Baker told William's inquest, which resumed on yesterday.

"It was a scream and it was silence pretty quickly ... I had no reason to think it was William."

Her large property is situated about four kilometres from Kendall, where William's foster grandmother lived.

William was playing at his foster grandmother's home on the morning of September 12, 2014, when he disappeared.

No trace of him has ever been found and no person has ever been charged.

The inquest heard Ms Baker learned years later that the bushland behind her home had been home to Frank Abbott, a convicted criminal widely regarded in the community as a creep and danger to children.

That new information prompted her to report the scream to police.

She told coroner Harriet Grahame on Tuesday she was "100 per cent" certain it was a boy's scream.

"I stood up, looked in the direction of the cry and listened," she said.

"But I didn't hear anymore.

"It was pretty thick bush."

The friend who told Ms Baker about Abbott's residence in the bushland said "all the children" in nearby Johns River were warned to stay away from him.

Abbott is not listed on the witness list and is not expected to give evidence to the inquest.

A bid to add high-profile former detective Gary Jubelin to the witness list failed on Tuesday after an application by William's foster parents.

The former detective chief inspector led the police search for William from February 2015 until early 2019.

But Ms Grahame said she already had a significant amount of material based on Jubelin's investigations and he'd responded twice to written requests to present any further evidence he held on the case.

"In my view, there is little that can be gained that is already not contained in the written material," she said.

She added Jubelin's giving of evidence "at this point" could be a "significant distraction".

Her inquest was concerned about admissible evidence on the September 2014 disappearance, not opinions about how the police investigation had been run.

The court was told the foster family believed Jubelin was best placed to shed light on particular lines of investigation over the years and what lines of inquiry were still outstanding when he departed.

But counsel assisting the coroner Gerard Craddock SC said police ran a criminal investigation "from the get-go" and the suggestion otherwise was "completely and utterly wrong".

Mr Craddock said the former detective had been "absolutely dedicated" to finding what happened to William and unsurprisingly had "opinions", but wouldn't be able to add anything new.

Jubelin was sidelined from the Tyrrell investigation in early 2019 and quit the force entirely in May 2019 after investigations began into illegal recordings he'd made while interviewing a person of interest.

He was later convicted and fined $10,000 for breaching of the surveillance devices act.

Australian Associated Press