The grim reason why the mystery of William Tyrrells disappearance 10 years ago may never now be solved

William Tyrrells remains would have vanished years ago even if they werent scavenged by wild animals, an inquest into his 2014 disappearance has been told.

The coroners inquest resumed this week to probe the mystery of how the three-year-old vanished from his foster grandmothers home in Kendall on the NSW mid north coast 10 years ago.

Forensic anthropologist Dr Jennifer Menzies told the hearing on Tuesday the toddlers bones would only have survived up to seven years in bushland.

She said the skeletal remains of a child could withstand weather and other factors in the open for that long before disintegrating.

But there were elements like exposure to sunlight, highly acidic or alkaline soil, high temperatures and animal predation would speed up their destruction.

Dr Menzies said that childrens bones were more likely to disintegrate before an adults because they had  lower mineral and higher organic content.

But she also said animals could have been taken the childs remains up to 3km away. 

Other factors could have also obscured or destroyed a childs body dumped in the bush, like leaf litter, roots of plants or trees growing around the body, branches falling from overhead.

Bones of a child like William disintegrate faster than adults bones because they have a higher organic and lower mineral content

The inquest has heard that Williams remains could have lasted in the bush for seven years, or might have disintegrated due to environmental or predation factors

She also said the remains could have moved or obscured by ants or termites, rain run-off, wind-blown sand, digging by rabbits, wombats, dogs, or foxes.

The inquest is currently investigating the police theory that William Tyrells foster mother buried his body in bushland after he fell from a balcony and died on the morning he vanished. 

Dr Menzies was asked by the William Tyrrell task force, Strike Force Rosann, in 2012 about what might have happened to Williams bones. 

Counsel assisting the inquest, Gerard Craddock SC, asked Dr Menzies whether injuries sustained prior to death - known as perimortem trauma could accelerate decomposition of remains.  

Dr Menzies said some studies found early exposure of bones accelerated decomposition because of insects.

Other studies found no difference when perimortem trauma was present.

Mr Craddock told the inquest when reopening on Monday that the police theory was that William must have died at [his foster grandmothers home at] 48 Benaroon Drive [in Kendall].

The theory... police assert is that she must have quickly resolved that if the accidental death of William was discovered she might lose Lindsay.

Lindsay - not her real name, which cant be revealed for legal reasons - was another foster child in the care of the foster mother at that time, who also cant be named.

Police assert that in that frame of mind, [the foster mother] placed William in her mothers car, said Mr Craddock.

After alerting [a neighbour] to Williams disappearance, [she] drove her mothers car to Batar Creek Road and placed Williams body somewhere in the undergrowth.

Police dog handler Senior Constable Matthew Gates, who the day after the disappearance searched the area where police theorise Williams body was dumped, was asked if William could have got that far through dense bush.

SC Gates, who said he found it hard to get through foliage almost as high as him let alone for a three-year-old to fight his through the bush, found the idea yes, impossible.

The inquest into William Tyrrell s disappearance will probe the police theory that his foster mother buried his body in bushland after he fell from a balcony

Professor Jon Olley, a water science expert, at the William Tyrrell dig in 2021, gave evidence on Monday in the latest round of inquest hearings

Police in 2021 search the Kendall house from where William vanished in 2014, theorising that he may have fallen from the balcony in an accidental death

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Williams foster parents are attending the hearings, as are detectives from Strike Force Rosann, and its boss Detective Chief Inspector David Laidlaw

The inquest into the disappearance of three-year-old William Tyrrell (above) has resumed for its final set of hearings in November and December

Mr Craddock has said the area around Batar Creek Road had been extensively searched by police who did not believe any trace of William was left there.

He also said that in the search for William after his disappearance - with police, fire fighters, cadaver dogs, chainsaws and hydraulic equipment – meant that the little boy had not simply just been lost in the search area.

William under his own steam could not travel beyond the area of the intensive search, he said. The conclusion there must have been human intervention.

Its beyond argument that no eye eyewitness can provide an account about how he left the boundaries of 48 Benaroon Drive.

The inquest, which began in 2019 but has been beset by protracted delays has now entered its final block of hearings, which will be held this week, and over a week just before Christmas.

Williams disappearance has become one of Australias most notorious missing persons cases.

The inquest before Deputy State Coroner Harriet Grahame – examining Williams disappearance and suspected death – was delayed last year when prosecutors weighed up charges against the boys foster mother.

A police theory is that William fell from the verandah of his foster grandmas Kendal home and afterwards his body was disposed of allegedly by his foster mother (above, with the foster father) 

Williams foster mother and father have continuously denied the allegation they played a part in his disappearance or any wrongdoing.

The inquest originally began in 2019 and ran for 18 months before it was adjourned in October 2020 and Ms Grahames findings were due to be handed down in June 2021.

The inquest was pushed back for police to begin the fresh investigations in late 2021 that involved searching new locations around Kendall.

On the fresh dig, teams scoured the garden of his foster grandmothers home and nearby bushland, but did not report finding anything of significance. 

The inquest was then pushed back again, as prosecutors weighed up the evidence concerning the missing boys foster mother.

Last year, police handed a brief of evidence to the Director of Public Prosecutions that recommended Williams foster mother be charged with perverting the course of justice and interfering with a corpse.

 Around that time, the foster parents solicitor Rylie Hahn called for police to disclose any evidence. 

Williams foster mother and foster father hold the position of calling for the disclosure of evidence which police suggest forms the basis of criminal proceedings, Ms Hahn said last year.

We are midway through the inquest and William remains missing and his case unsolved.

Williams foster mother maintains she had nothing to do with his disappearance … and asks the police to continue to look for William and what happened to him.

Then in August this year, Ms Grahame was handed a letter from the DPP, outlining the status of that request for advice.

William Tyrrell, dressed up as his favourite character, in a photo not long before he disappeared while playing on the verandah in Kendall, on the NSW Mid North Coast with his grandma and his sister

In the letter, the Director of Public Prosecutions, Sally Dowling SC, said that NSW Police had in April asked her office to suspend its request for advice until the conclusion of the final block of inquest hearings. 

In 2022, Williams foster mother was found not guilty of lying to the NSW Crime Commission.

In November last year, Williams foster father was also acquitted of five counts of lying to the NSW Crime Commission.

The court was told at the time that during the Crime Commission hearing, counsel assisting, Sophie Callan SC, questioned the foster mother about whether William had fallen from the balcony and she had disposed of the body.

The couple denied any wrongdoing or disposing of his corpse.