The skeletal remains of the child, who police believe to be a Caucasian girl, aged two-and-a-half to four, with fair, 18 cm (7 inch) long hair, were spotted by a driver on South Australia's Karoonda Highway, 2 km (1.2 miles) west of the town of Wynarka on July 15.
Near the body was a faded, greying black suitcase, the quilt, and items of children's clothing, including a black party dress and a Dora the Explorer T-shirt.
Detective Superintendent Des Bray, who is heading the investigation, said at a press conference that the suitcase was first seen at the location after road works were completed in March.
Investigators believe the suitcase containing the body and clothing was left behind a bush, before another person subsequently tipped out most of the contents and left the suitcase near the roadside.
Bray said that, for reasons he would not disclose, police were "confident that this child was murdered," and that the killing had occurred at another location.
Quilt pattern revealed
On Monday, police released an image of the tattered 90 cm by 90 cm patchwork quilt, with seven of its 25 octagonal patches digitally enhanced to show designs including pumpkins, stars and a camel.
The quilt's border features a pattern of musical notes.
Bray said Sunday that the quilt had been homemade, and appealed for anyone who recalled having seen it to come forward.
"Clearly somebody has gone to the effort of making that quilt for somebody that they care about and love," he said.
"It's extremely distinctive and it's impossible to believe that somebody doesn't know who had that quilt."
A child's black party dress found with the body should also be recognizable to somebody, he said.
"A little girl wearing that dress -- people must remember seeing a little girl like that at a party, at a barbecue, at a family get together."
Madeleine? 'Highly unlikely'
The description of the murdered girl -- who police say was 90-95 cm (2 feet, 11 inches -- 3 feet, 1 inch) tall, and killed some time since the start of 2007 -- triggered speculation that the remains could be those of missing British girl Madeleine McCann.
McCann, who was also blonde, disappeared during a family holiday in Portugal in May 2007, aged three.
But Bray said the investigation was proceeding on the basis that it was probably an Australian child.
"It is highly unlikely that the victim in Madeleine McCann," he said.
32 children excluded
Police have said that they have received a huge public response to their appeal for information, with 410 calls from members of the public.
The calls had led to 32 children being ruled out as potential victims.
"We've had a large number of children identified to us who may have been children at risk or children that people are on reflection worried about," Bray said.
Police are also appealing for a man who had been seen in the area with a dark suitcase in April and May to come forward, to potentially exclude him from the inquiry.