'Supt Wilde also revealed Cleo’s voice was heard on the CCTV footage from nearby beach shacks the day before she disappeared.
“It was just after they arrived, it’s motion-sensitive so it was by (their vehicle),” he said.
“It’s very limited … we’ve reviewed that and we believe it’s Cleo’s voice that’s heard on the CCTV.”
Det Wilde said he could not reveal what was said in the footage but police had other evidence from Cleo’s parents that had put her at the scene.'
Lead investigator Det-Supt Rod Wilde of the major crime division is expected to fly to Carnarvon on Thursday.
Forensic police revisit Smith home, Blowholes camp
Forensic police collected ash samples from fires at the Blowholes camp grounds on Wednesday, hours after investigators searched the Carnarvon home of missing four-year-old Cleo Smith for a third time.
thewest.com.au 'Officers also returned to the Blowholes camp site about 70km north of the town to collect samples from some of the campfires at the site. They stayed in the area for a few hours before leaving about 5.30pm on Wednesday.'
Cleo's case was raised in Federal Parliament on Wednesday, with Home Affairs Minister Karen Andrews saying the government was strengthening laws to give agencies greater scope to act in the case of crimes against children.
"The AFP and federal agencies will always be ready to support state work of state police forces when it comes to crimes against children and they are currently doing that in the case of four-year-old Cleo Smith, who disappeared from a campsite in Western Australia," she said.
Mr Blanch said police wanted to "eliminate everyone at the campsite to see what their movements were, why were they there (and) where did they go afterwards".
Police are also desperately trying to speak to a driver who was seen heading away from the campsite 10 days ago.
The car was seen heading south along Blowholes Road, from the Blowholes Campsite where Cleo's family were camping, and towards Carnarvon.
CCTV from homes and businesses along the Coastal Highway is currently being reviewed by officers in an attempt to find the car's registration or driver.
"That's what the team have been focused on in relation to the CCTV along the entire highway... to corroborate what was witness observations of a vehicle at that time on the highway," Mr Blanch said.
"If anyone saw car movements at or around 3am heading south on the coastal highway from Blowholes Road, that is really one of our investigative areas of focus.
'It's not to say that we're saying that that is the person, but certainly driving around at 3am coming out of there would pique our interest as to who it was and what they were doing there and maybe what they saw themselves."
Prime Minister Scott Morrison revealed yesterday the Australian Federal Police (AFP) is using secret technology in the search.