A dusty balance bike leaning against a wall is a heartbreaking reminder of little Gus Lamont, the toddler who vanished without a trace from a remote South Australian sheep station just under a year ago.

In an exclusive interview with 7NEWS, Gus’s grandmother Josie Murray has spoken again, inviting cameras onto the property near Yunta for the first time to show areas never before seen by the public.

WATCH THE VIDEO ABOVE: One year since Gus Lamont vanished without trace

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“It brings me to tears that he’s not here,” Murray said as she showed 7NEWS the area where the little boy was playing on the afternoon before he disappeared.

“Just down here. And then that was the last he was seen, and after that he just disappeared.”

7NEWS had exclusive access to the property where the three-year-old vanished this time last year. Credit: 7NEWS

Gus vanished on the evening of September 27 — AFL grand final day — last year while in the care of his other grandparent, who was looking after him and his baby brother at the homestead. The alarm was raised, sparking the largest police search in South Australia’s history.

Murray revealed police have told her she is the main suspect in the case, which has been declared a major crime. But she insists she’s innocent.

Gus’s grandmother Josie Murray has been named the main suspect but insists she's innocent. Credit: 7NEWS

“As far as I’m concerned, I still want to know the answer, what happened to him,” she said.

Murray believes Gus was abducted by a stranger.

“I think he has to have been taken,” she said. “Nothing else makes sense.”

7NEWS was shown the shearing shed on the property where Murray and Gus’s mother were working on the day he disappeared, located about 15km from the homestead. They were there for several hours, returning at about 5.30pm to discover Gus was gone.

Twelve months on, still no clues have been uncovered, not even the hat he was wearing that day.