This is the equipment police hope they can help break through after seven years of deadlock.
And, the officers returned to where it all began – the front yard of William Tyrrell’s adoptive grandmother’s home – to use it.
William went missing at the age of three in September 2014, and despite a massive police investigation, no one has ever been charged and no body has been found.
Today, specialists from the Australian Federal Police (AFP) joined the operation.
Rural Law Enforcement and Fire Service (RFS) volunteers are expected to search for three new locations in and around the town of Kendall on the north coast of New South Wales over the next three weeks .
“There will be a number of strategies used by police and other agencies to clear the ground and go underground in the number of places,” Detective Chief Superintendent Darren Bennett said this week.
Here are some of the tools they will use.
Corpse dogs were brought in to roam parts of the front yard, particularly the garden beds and an area under the balcony of the house.
They were also taken to the bush about 1 kilometer from the house.
They are trained to find the scent of a rotting body, then alert their master to the location of the remains.
They can sniff out remains that are decades old, even if they are buried.
Even with advancements in technology, dogs are still considered one of the best odor detection tools in law enforcement.
Cadaver dogs can detect the smell of human remains, blood, a decomposing victim’s clothing, or human fluids associated with the remains.
Police dogs were brought to the scene shortly after William went missing in 2014 and detected his scent, but only within the property lines.
Forensic investigators used a substance called luminol around the front garden of the house on Benaroon Drive.
William’s adopted grandmother had lived on the property. She passed away in March.
Luminol is a substance used to find traces of blood and can give detectives clues to escape routes from crime scenes or if a body has been dragged somewhere.
It reacts with the iron in hemoglobin, a protein found in red blood cells.
Traces of blood emit a blue glow when sprayed with luminol.
Luminol is especially useful if there are only small traces of blood that are not visible to the human eye or if an attempt has been made to clean the blood.
Ground penetrating radars
Ground penetrating radars (GPRs) use radio waves to capture images below the earth’s surface.
They are a key tool for investigators trying to locate buried objects and can even identify if a hole has already been dug in one location.
They can detect objects under wooden floors and brick or concrete walls and have been used in many cold cases if someone is believed to be buried.
GPRs avoid lengthy and costly searches and have been used by British police in their investigations into notorious serial killer Fred West.
Using radar technology, officers were able to discover the bodies of nine women in the backyard of West’s home in Gloucester, known as the ‘House of Horrors’.
Screeners, metal detectors and drones
Police are also using sieves to scan the floor of the Kendall property for clues.
This is a tool commonly used by forensic teams, but it can be time consuming as it involves sifting through massive amounts of dirt and debris.
Police were seen yesterday sifting dirt from the garden bed at Kendall’s house.
Metal detectors are also in use on the property and AFP uses drones to monitor the area.