I think you're right and also the Australian Defence Force was brought in to help.The family didn't want people helping from the get go. They wanted to deal with it themselves. So it was the police who were in charge of the search and, from what I gather from media reports, approved the volunteers searching. Even the guy who'd had 20 years SES experience had to get approval to search.
Hopefully the family didn't mind the Defence Force lending a hand?