In the video, released by NSW police this morning, William's parents say they still hope their son is alive.

“If somebody has him and if he’s alive ... I want him to be safe, I want him to be feeling loved and I want someone to be looking after him ... because to imagine that something else is going on ... we can’t live a life like that,” William’s mother said.

“Just give him back ... give him back. “Take him to a church, take him to a police station, take him to a school. “Give him to someone ... give him back,” she begged.

William’s mother says when he failed to respond to her calls as he played outside just metres away, she knew he’d been kidnapped.