Police promise to continue investigations into the disappearance of a preschooler from an outback property despite scaling back the search.

August, known as Gus, went missing from his family's sheep station in the remote South Australian mid-north on Saturday afternoon.

The only trace found of the four-year-old was a tiny footprint in the dirt about 500 metres from the family homestead amid an extensive week-long ground and air search.

"We will not rest until we can try and find the answer to why Gus has been missing, and hopefully, like I said before about the family, return him to them," SA Police Assistant Commissioner Ian Parrott told reporters on Friday.

"We will now transition into investigation focus, (and) we will now continue to pursue ongoing lines of inquiry."

Police are co

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