From the 13 unanswered questions link:
Where had they been living?
The mother and daughter were from Alice Springs but had left in search of work. The pair travelled to Adelaide in November, 2008. It is unknown how long they stayed in the city before travelling to NSW, where Karlie’s body was found.
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Speculation and opinion only. The murderer was in Adelaide. Karlie and Khandalyce were killed there. Karlie was taken to NSW and dumped in Belanglo as a red herring. After the killer thought long enough had passed he dumped Khandalyce closer to home. Is he getting old? Afraid of being discovered?
When were those barrel murders in Adelaide? Too long ago?
Edit: yes, way too long ago.