WA girl's abduction likely 'opportunistic'

Police have interviewed more than 110 people who were at the Blowholes campsite on the night Cleo arrived with her family on October 16.

The little girl was last seen in her family's tent, at the vast campsite on WA's northwest coast, around 1.30am that night.

Detective Superintendent Rod Wilde says the family had stayed near their tent all evening and had not socialised with other campers.

"I think it's more than likely an opportunistic-type event," he told Perth radio 6PR on Tuesday.

"We know they got there on the Friday night, it was getting dark, and there would have been limited opportunity for people to observe Cleo at that time."

Police have stressed the girl's mother, Ellie Smith, and her partner, Jake Gliddon, are not suspects, nor is Cleo's biological father.

Investigators have spoken to the vast majority of people who were at the campsite, but are still yet to hear from the driver of a car seen leaving in the middle of the night.

"We've had over 1000 calls to Crime Stoppers from the public," Supt Wilde said.

"We've still got a long way to go, a lot of work in front of us but we're making progress."

Police this week collected more than 50 cubic metres of rubbish from roadside bins stretching from Minilya to Geraldton.

It was transported to Perth, where forensic officers and recruits sorted through hundreds of bags in search of items that may help them find Cleo.

The state government is offering a $1 million reward for information leading to Cleo's location.

Police say the girl's disappearance was immediately treated with the highest priority, although it took two hours to establish a roadblock at the site.

Detectives have made several visits to Cleo's family home in Carnarvon, sought CCTV footage from a range of businesses in the area and collected samples from a campfire at the Blowholes site as the investigation continues.

Australian Associated Press