But police insist investigations are continuing in the hope the young boy is still alive.

The announcement comes more than a year after the then three-year-old vanished from his grandmother's home at Kendall.

On Tuesday, William's parents thanked members of the Kendall community who helped in the search for the missing boy and had given their support.

"We love William. And when he was home, we treasured every second of every day with him," they wrote in an open letter.

"Now, with William missing, we are faced with having to live our lives as a family incomplete.

"We have to face holidays, sunrises, sunsets without him. New Year's without William. A Christmas without him. A birthday for William but without William."

On the anniversary of  his disappearance communities across the country walked in tribute to the four-year-old.