A child allegedly assaulted and intimidated by William Tyrrell's former foster parents can be heard sobbing and begging with them in audio played to a court.
The 58-year-old woman pleaded guilty on Monday to assaulting the child, who is not William, on two occasions in January and October 2021.
She is still fighting two charges of intimidating the victim in a series of incidents between January and August that same year.
Her 56-year-old partner, William's former foster father, has pleaded not guilty to one count of assault and one count of intimidation over alleged conduct in November 2020 and October 2021.
Neither foster parent can be named for legal reasons.
In recordings played in Parramatta Local Court on Tuesday, the child could be heard crying and begging with her two carers, at one stage pleading with them to let her go.
Prosecutor John Marsh said covert recordings had been made of conversations within the foster parents' house on Sydney's north shore.
Police also secretly recorded conversations in their car and during telephone calls as part of their investigation into William's 2014 disappearance.
"Investigators obtained evidence of a number of assaults and offences of intimidation," Sergeant Marsh told magistrate Susan McIntyre.
In the recordings, the foster father is heard screaming at the child to get in their car, saying he is "done" and calling the child a "f***ing stupid little s***".
"We've done nothing to you," he was heard saying.
"All we've done is support you. We feed you, we house you. You treat us like s***."
In a separate recording, his partner yells at the child to stop talking.
"No, you don't get to talk," she said to the youngster's cries.
"You are not talking. You have no voice until I tell you."
In another recording, she said: "I am stronger than you. I will outlast you. You will not beat me at this."
In November 2021, police met with representatives from the NSW Department of Communities and Justice who removed the child from the foster parents' home.
The woman spoke with police and admitted certain aspects of the offences while the man continued to deny any wrongdoing.
In August, police dropped one charge against both the man and the woman of dishonestly obtaining a financial advantage or causing disadvantage by deception.
At the time, the couple said they would plead guilty to downgraded charges of procuring another person to make a bid on behalf of a seller at auction, which will result in a fine.
The pair paid a dummy bidder to bump up the auction price of their north shore home in December 2020.
Mystery surrounds the 2014 disappearance of William Tyrrell, who was three years old when he vanished from a property belonging to his foster grandmother at Kendall on the NSW mid-north coast.
Police have sought answers in the years since his disappearance, including conducting a thorough search of the Kendall property in December 2020.
Neither foster parent has been charged in relation to that case, however the mother was acquitted in 2022 of lying to the NSW Crime Commission about hitting another child with a wooden spoon.
The hearing on the assault and threatening charges continues.
