Forensics police officers are at the home of missing four-year-old Cleo Smith

WA police probe whether the family of the missing four-year-old was being watched in the days before camping trip.

Missing girl Cleo Smith, 4. Picture: Instagram

Officers from the forensics division of the West Australian Police Force are at the family home of missing four-year-old Cleo Smith in Carnarvon, about 890km north of Perth.

Cleo vanished a week ago from a tent at the Blowholes Campground about 45 minutes by car north of the fruit-growing town of Carnarvon. She was camping with her mother Ellie Smith, her stepfather Jake Gliddon and her baby sister Isla and they were all in the same tent with a divider. Ms Smith has given a harrowing account of waking at 6am on October 16 to find Cleo gone and the tent flap “completely open”. She and Mr Gliddon are pleading for anyone with information that could help the investigation to report it to police.

A police source told The Australian on Saturday that forensics officers are at the family home primarily to try to establish if anyone may have been watching the house in the days before the family went camping. Their work at the home on Saturday includes fingerprinting the outside of the house and perimeter fencing.

Teams of volunteers and mounted police have searched for Cleo. Picture: The West Australian

The land search for Cleo at and around the campground was one of the biggest in the state’s history. It was scaled down late on Friday and the campground is again open to the public.

Police have repeatedly said they are open minded about what happened to Cleo but their words and actions in the days after she disappeared suggested they had grown convinced she was taken from the tent and did not wander off.

Cleo Smith’s mother Ellie Smith and her partner Jake Gliddon. Picture: Supplied by ABC News/James Carmody

Cleo’s sleeping bag disappeared with her and it has not been found. The tent flap closest to the mattress that Cleo went to sleep on was open to a height that she could not have reached herself.

As police examine large volumes of electronic data from cattle grids in the region that record number plates, roadhouse CCTV and dashcam footage, the McGowan government is offering a $1 million reward for information that leads to Cleo’s return or the arrest and conviction of anyone involved in her disappearance.