Strike Force Rosann's Detective Inspector Gary Jubelin yesterday confirmed what his superior revealed on the weekend.

Commander Mick Willing said the search for the boy who went missing from his grandmother's Kendall front yard on September 12, 2014 was "one of the biggest investigations being run by homicide".

The strike force consists of specialists from the State Crime Command in Parramatta as well as detectives in Port Macquarie, though Det Insp Jubelin could not yesterday detail their specific roles.

There are now 12 officers permanently attached to it, a number Superintendent Willing attributed to Det Insp Jubelin approaching him and the command.

Where's William? campaign spokeswoman Hetty Johnston said the Tyrrell family have never doubted the abilities of the police.

"More than anything else, this just confirms what they have known all along and that is that the police are doing everything, absolutely everything they can to bring this little boy home," she said.

Mrs Johnston backed police calls via a statement issued on February 16 for the community to consider William alive and to not give up on him.

"NSW Police maintain the position that until they have conclusive evidence that William Tyrrell is deceased, they will continue to investigate the matter on the basis William could still be alive," the statement read.

"However, we do not have evidence he is deceased so any commentary in this regard is speculation."

Any one with information is urged to contact Crime Stoppers on 1800 333 000 or report online at nsw.crimestoppers.com.au.