* William's foster parents, who can't be identified, were planning to take the boy and his sister to Kendall on Friday, September 12, 2014 but left a day early.

* They arrived at 9pm on September 11 and put the children to bed, no one including the foster grandmother had advance knowledge they would leave Sydney at that time.

* The foster mother awoke the next morning to the sound of William's giggle in a nearby room, got up and opened the sliding glass door.

* She noticed two cars, parked on the nearby street, one was white the other grey, parked close together. They were dirty, had missing hubcaps and tinted windows.

* She did not see number plates but instead went to get the children ready as her husband prepared for a business call.

* William's foster father went to nearby Lakewood about 9am for a solid internet connection for the call. He had a prescription filled at a chemist there at 10.19am.

* William and his sister started riding bikes on the driveway after he left.

* Another man drove past them in the dead-end street. The foster mother locked eyes with him as he continued down the road in an old teal-coloured car.

* William and his foster mother played a game called "mummy monster" where they would roar at one another.

* They explored the tree-lined yard as William's sister sat inside with their grandmother drawing art for their late grandfather's grave.

* William's foster mother made cups of tea before snapping the now iconic photo of the three-year-old boy sitting on the deck dressed as Spider-Man at 9.37am.

* As the woman and her mother drank tea William jumped around the deck, again roaring while playing a new game called "daddy tiger".

* She heard him roar, then silence so she raced around the house trying to find him in the yard. She then searched inside the home in every cupboard and under the house.

* She checked her phone and saw a text from her husband saying he was nearly home after stopping to buy some newspapers at a nearby store.

* She ran out the front and told her husband William was missing. He began searching yards while the foster mother alerted neighbours and then police.

Australian Associated Press