Crews scouring the Blue Mountains for missing schoolgirl Charlise Mutten are pushing through poor visibility and rain as the search enters its fifth day.
At a briefing at the Rural Fire Service (RFS) headquarters at Mount Wilson, volunteers were told the nine-year-old would be "extremely lethargic" if she were found and would need water immediately.
The ABC understands the rescue team is smaller because some of its members have had to self-isolate after becoming infected with COVID-19.
The Tweed Heads Public School student lives with her grandmother in Coolangatta in Queensland, but was holidaying in the Blue Mountains with her mother, Kallista Mutten.
The pair were staying with her step-father Justin Stein at his family's multi-million dollar estate on Shadforth Road when the girl disappeared last Thursday afternoon.
Ms Mutten reported her daughter missing to police the following morning but police haven't revealed whether she was formally interviewed since she was hospitalised for a medical condition days ago.
Criminologist Xanthe Mallett, who has followed the cases of other missing children including William Tyrrell, said with mild weather and some rain there was "every hope" she would be found alive.
But those chances were diminishing with each passing day.
NSW Police's reluctance to share its lines of inquiry has created an air of mystery around the schoolgirl's disappearance.
"They're keeping things very covert and very quiet, so that they can obviously manage the situation to best advantage to hopefully find Charlise as soon as possible," Dr Mallett said.
The girl's mother would be a crucial component of the investigation, the criminologist said.
"They will be looking to talk to her soon, because every day that passes, you know that the information that she holds could be critical into finding Charlise," she said.
Dr Mallett says there are lessons to be drawn from William's disappearance.
William was last seen playing in his foster grandmother's front yard in 2014 on the NSW Mid-North Coast. Despite extensive investigations and a renewed search in November, the boy's remains were never found.
"The days after William vanished, investigating avenues were lost, people maybe weren't interviewed as quickly as they could have been, the area wasn't secured as well as it should have been," Dr Mallett said.
"They'll be looking at every possible hypothesis, so that, you know, later on, they can rule those out as information becomes available to them."
