Police have searched homes in Canberra and South Australia in what they call a “fast-paced investigation” into the double murder of Karlie Pearce-Stevenson and her daughter Khandalyce.

Detective Superintendent Des Bray said the searches had been “extremely productive” and items were found that would assist in the investigation.

“Those premises belonged to people associated with Karlie and Khandalyce in some way,” he said.

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“I can’t go into the specifics of what those searches have been but I can say that those searches have been extremely productive.”

In a joint statement, New South Wales and South Australian police said they were pursuing a “very strong line of inquiry” but were keeping an open mind.

“We are also speaking to people who we suspect have knowledge of what has occurred to this young mum and her little girl.”

Police said they were looking at the possibility there was more than one person responsible for the murders.

Karlie’s remains were found in the NSW Belanglo Forest in 2010, while the remains of her daughter, Khandalyce Kiara Pearce, were found near a suitcase alongside the Karoonda Highway in SA’s Murray Mallee earlier this year.

Police believe the pair were most likely murdered in December 2008 because there were no confirmed sightings of them after that date.

Police still want to speak to man with suitcase

Following the discovery of Khandalyce’s body earlier this year, police have tried to establish the identity of a man, believed to be in his 60s, who was seen in the Wynarka area with a dark suitcase on two occasions.

Superintendent Bray said police now considered him “largely irrelevant but we would like to know who he is as a matter of completeness”.

“We can find out who it was and if he saw anything or, if he ever touched the suitcase, for example,” he said.

“We have been able to establish now that that man has been seen in that area before the suitcase was discovered by people travelling that road, and he continued to be seen after [that] carrying his suitcase up and down the road after the suitcase had been recovered.”