A helicopter pilot who was on the scene just hours after Cleo Smith disappeared says he knew the situation "wasn't good" after just an hour in the sky.
Pilot Justin Borg was in the air soon after the four-year-old was reported missing from her family's tent at the Blowholes campsite in Western Australia.
Speaking to the Today Show, Mr Borg said it was initially thought Cleo had wandered off and thought she would have been found "very quickly".
Mr Borg is familiar with the Carnarvon area and he said helicopters are a "great way" to search for people, especially when the terrain is like that of the local area.
"Once we hadn't located her after an hour it wasn't looking good," he said, adding no stone was left unturned in the search.
Cleo was last seen about 1.30am on October 16. Her mother Ellie Smith said she woke around 6am to discover the little girl was missing.
Police now believe Cleo was abducted from her family's tent.
Police are yet to hear from the driver of a car seen leaving the campsite around two hours after Cleo was last seen in her family's tent.
Anyone who was in that vehicle is being urged to contact police.
"The priority for the investigation at this time is for everyone that was at the campsite during that morning to come forward to police," Mr Blanch said.
"We need to speak to every single person that was there and we haven't yet done so."
Mum pleads for daughter's return
An official search operation in the vicinity of the campsite has concluded but deputy police commissioner Col Blanch said there had been a "monumental effort" to assist police, especially by locals in Cleo's nearby hometown of Carnarvon.
"Everyone in the community has really rallied together to help," he told reporters on Monday.
Ms Smith has shared several heart-wrenching Instagram stories about her missing daughter.
"We all need her home," one caption said, along with photos of Cleo and her sister Isla.
In another story, Ms Smith shared more photos of her two daughters, saying Cleo is the "best big sister ever".
On her social media, Ms Smith has also shared the police notice which offers a warning $1 million reward for information which leads to Cleo's return.
"Any information big or small, find my little girl," Ms Smith wrote.
Cleo's voice heard on CCTV before disappearance
Police have confirmed the voice heard on CCTV footage from a beach shack just metres away from the campsite belongs to Cleo.
According to the West Australian, the motion-sensitive camera faces the beach shack which is about 20 metres away from where Cleo and her family were staying.
Police reportedly confirmed Cleo's voice is heard on the footage they obtained from the camera.
The audio confirms the four-year-old was at the campground before she disappeared, ruling out suspicions she was never there in the first place.
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