William Tyrrell’s 10-year-old sister has made an emotional promise to find her sibling, telling an inquest into his disappearance she wants to become a detective and solve the case.

The pair were playing “tigers” on the lawn of their foster grandmother’s home at Kendall, on the NSW Mid-North Coast, when the three-year-old vanished in September 2014.

William’s sister, who cannot be named for legal reasons, recorded a message that was played at the end of a 19-month inquest into the three-year-old’s suspected abduction.

“I hope this speech makes you solve the case,” she said.

“If it doesn’t, when I am officially adult, I will be in the police force, a detective specifically, and I will find my brother and not give up until he is found.

“Please help my family, most of all me, find our precious William.”

William’s foster grandmother had been supervising the pair, but when she went inside to make a cup of tea, the little boy disappeared.

William Tyrrell was playing in the backyard of his foster grandmother’s home when he vanished.

Police have identified hundreds of persons of interest in the years since, but no one has ever been charged.

William’s foster parents – who cannot be named for legal reasons – became emotional as they handed a book of photographs to Deputy State Coroner Harriet Graham as she closed the inquest at Lidcombe Coroners Court, in Sydney’s west, on Thursday.

“William was a jovial and boisterous little boy, his sense of humour and cheeky antics always made us smile,” the foster father said.

“His giggles were infectious, everyone loved being around him, including us.”

The initial search went for nine days before the foster family were forced to return home to Sydney.

“William’s empty car seat in his sister’s next to the back seat absolutely tore our hearts,” the foster mother said.

“She continued to ask where her brother was… she was deeply missing her best friend… and we had no answers.”

“Our family was living a nightmare,” she said.

Their testimony was followed by a statement from William’s biological parents, read out by their lawyer Michelle Swift, who was joined in the witness box by the biological grandmother.

William was put into foster care not long after he was born, and the court heard his biological father “has never been the same since”.

“It was a traumatic experience for both. Having William taken away broke his heart. He may never stop hurting,” the statement read.

“We have had six years of pain and broken promises – we are still grieving, we are angry and frustrated, and we want answers.

“We want to thank the coroner, we think she cares.”

Deputy State Coroner Graham acknowledged the suffering endured by both families and thanked them from sitting through more than a year and a half of “harrowing” evidence.

The coronial findings will be handed down on June 18, 2021.

-ABC