Police use high-tech equipment as they scour William Tyrrell’s foster grandmother’s yard

A forensic expert has revealed detectives are likely sifting through soil to find human remains at the property where William Tyrrell disappeared seven years ago.

Police arrived at the missing child’s foster grandmother’s home on the NSW mid-north coast on Tuesday where they were pictured filtering through dirt around the house and gardens with large sieves. 

They were also seen using levellers, drones, and other machinery on Wednesday as they continued to search the Kendall property where the boy was last photographed.

The practices are largely used by experts when looking for human remains including small bones and teeth, according to Professor David Ranson from the Victorian Institute of Forensic Medicine. 

‘They’ve publicly said they believe he is dead and therefore to understand how he’s died the body is a very important piece of potential evidence in finding out what happened,’ Professor Ranson told Daily Mail Australia. 

‘Efforts are being directed towards locating and identifying the body.’ 

A forensic expert has revealed detectives are likely sifting through soil to find remains at the property where William Tyrrell disappeared seven years ago

Volunteers from the Rural Fire Service search William's foster grandmother's home in Kendall on Tuesday

Volunteers from the Rural Fire Service search William’s foster grandmother’s home in Kendall on Tuesday

The practices are largely used by experts when looking for human remains including small bones and teeth

The practices are largely used by experts when looking for human remains including small bones and teeth

William went missing wearing his Spider-Man suit while playing at his foster grandmother's home in 2014 in Kendall, about 40kilometres south of Port Macquarie

William went missing wearing his Spider-Man suit while playing at his foster grandmother’s home in 2014 in Kendall, about 40kilometres south of Port Macquarie

The forensic expert said small human remains can often be scattered via moving soil or animals and revealed the variety of technologies and tools detectives use to trace a body. 

‘They’ll be using remote procedures including images from the sky, light planes or drones, changes in vegetation and changes in landscape which might suggest a clandestine grave,’ Professor Ranson told Daily Mail Australia.

‘Then you require ground searches, trying to locate forms of investigative information.

‘There are also techniques used to identify biological material or blood, but after seven years it’s really difficult to find these things.’

The type of soil at the property and the condition it is in also is crucial to detectives given different variants of dirt will have different effects on human remains.

Professor Randon said the way a body is buried has a huge impact on its preservation. 

‘It’s important because depending on the way in which a body has been placed in the ground, it may be on the surface and may be deep down, that results in different degrees of preservation,’ he said.

‘A deep burial might see a body preserved well, whereas superficial burials covered by leaves and branches you potentially have a lot of insect and animal interference. 

Police arrived on Tuesday with cadaver dogs as their massive search of the property and surrounding areas began

Police arrived on Tuesday with cadaver dogs as their massive search of the property and surrounding areas began

Experts used UV rays to attempt to locate blood sources, something Professor Ranson says would be difficult after seven years

Experts used UV rays to attempt to locate blood sources, something Professor Ranson says would be difficult after seven years

The forensic expert said small human remains can often be scattered via moving soil or animals, with the potential for having to follow animal tracks into burrows if they think large parts could have been carried

The forensic expert said small human remains can often be scattered via moving soil or animals, with the potential for having to follow animal tracks into burrows if they think large parts could have been carried

William Tyrrell (pictured) went missing from his foster grandmother's home seven years ago

William Tyrrell (pictured) went missing from his foster grandmother’s home seven years ago

Authorities have access to the country’s best technology in their search, incuding heat detection devices, vegetation regrowth analysis, ground contour changes and other aerial photographies. 

Professor Ranson said the responsibility of forensic experts is to ‘reconstruct’ the events before a potential death rather than the cause. 

‘The tasks of the forensic person is to reconstruct the circumstances surrounding the death, it’s not so much about the cause of death,’ he explained.

‘They’ll look at injury pattners, what do they mean in terms of causation of the injury and then apply forensic work in relation to fractures. 

‘If you find a skeleton or areas of haemorrhage in the body, what trauma can lead to that.’   

Drones have been used to monitor changes in vegetation in the area which may provide hints to where a body could be located

Drones have been used to monitor changes in vegetation in the area which may provide hints to where a body could be located

Authorities have access to the country's best technology in their search, incuding heat detection devices, vegetation regrowth analysis, ground contour changes and other aerial photographies

Authorities have access to the country’s best technology in their search, incuding heat detection devices, vegetation regrowth analysis, ground contour changes and other aerial photographies

Professor Ranson said the responsibility of forensic experts is to 'reconstruct' the events before a potential death rather than the cause

Professor Ranson said the responsibility of forensic experts is to ‘reconstruct’ the events before a potential death rather than the cause

Police have seized a Mazda (pictured) that once belonged to William Tyrrell's foster grandmother, who died earlier this year

Police have seized a Mazda (pictured) that once belonged to William Tyrrell’s foster grandmother, who died earlier this year

William went missing wearing his Spider-Man suit while playing at his foster grandmother’s home in 2014 in Kendall, about 40kilometres south of Port Macquarie.

On Wednesday police seized a car that once belonged to the foster grandmother of missing William Tyrrell as the search for the boy’s remains enters its third day.  

Tyrrell’s foster grandmother died aged 88 in March and it’s understood her car was seized from a person unrelated to the investigation.

Police are now probing new theories about William’s mysterious disappearance as detectives continue to scour the property where he went missing.

They include the theory William fell from a balcony at the home of his foster grandmother, who died in March this year aged 88. 

The timeline of events after William Tyrrell disappeared from the Kendall home more than seven years ago

The timeline of events after William Tyrrell disappeared from the Kendall home more than seven years ago

***
Read more at DailyMail.co.uk