Researchers tore bushland with rakes and spades, dug up the garden of the house and deployed Luminol, a technology designed to detect blood spatter.
The police recently returned to the city, with the investigation still active.
No evidence of William was found. Long-term Strike Force Rosann investigator Detective Sergeant Andrew Lonergan told the Downing Center Local Court this week SD remains firmly in the frame.
“I have formed the view that SD knows where William Tyrrell is,” he said under cross-examination.
Lonergan and Sergeant Scott Jamieson visited SD’s home in Sydney in November last year to summon her before the Crime Commission, telling her they knew what had happened to the little boy.
“We know why, we know how, we know where he is,” Jamieson said. “We say we know what happened and why it happened and where [his body] is.”
In response, SD asked, “Then why don’t you have him?”
Jamieson told the court this week that he did not deliberately lie to SD.
When she appeared before the secret hearing of the Crime Commission, a distressed SD repeatedly denied dumping the body of the little boy, who came into her and her husband’s care at nine months old.
“I didn’t take William, I didn’t dump his body, I didn’t, I didn’t have it. I don’t know where he is,” she told the Crime Commission hearing.
Part of the strike force’s motivation to charge SD with providing false information was to pressure her to reveal William’s whereabouts, Lonergan admitted this week.
“Our main objective was to find William Tyrrell,” he said.
Along with lying to the Crime Commission, SD has been charged by detectives investigating William’s disappearance with two counts of common assault and two counts of intimidation.
The charges relate to another foster child – a 10-year-old girl – who kicked, punched and hit SD with a wooden spoon.
A secret recording taken at the couple’s home is said to capture the girl crying “no, please, no” and sobbing as she is hit with the spoon. A second secret recording, from a phone tap, allegedly captured SD telling her husband to say the couple had a “big problem” because the girl had a “massive welt” on her leg.
William’s foster father, known by court order as JS, is also accused of lying to the Crime Commission and common assault, and will face court next year.
Meanwhile, the strike force – which has repeatedly targeted a support group of grandparents, an elderly neighbor and a washing machine repairman who was at a school assembly when Willem disappeared – remains steadfast in its focus on SD, who’ t was cleared as a suspect by former chief investigator Gary Jubelin years ago.
Jubelin has since left the police and has been convicted of illegally including a suspect in the case.
Despite police interviews numbering in the thousands, several large-scale searches and an eight-year investigation, one question remains – where is Willem?
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