The body of an Adelaide man who police believe was assaulted and murdered in a drug-related attack is likely near the town of Orroroo, investigators say.
The mother of Robert Atkins, 29, said she had not seen her son for two months when she reported him missing in January.
Police have previously said they suspect he was held captive and assaulted for up to a week at a house at Christie Downs, in Adelaide's southern suburbs, in November.
In early August, police said he had likely been moved to another property at Seaford before being driven to Port Pirie, where he was murdered.
"The investigation into the murder of Robert Atkins is progressing very well," a police spokeswoman said in a statement.
Orroroo is a community of about 600 people north of Jamestown in South Australia's mid-north.
The spokeswoman said while officers could not go into detail about the investigation for operational reasons, they were working to reduce the likely search area.
Police have alleged Mr Atkins' murder was related to the drug scene in Adelaide's southern suburbs.
Earlier this year, officers released images of two vehicles they believe were connected with the murder.
A black 2010 Jeep Cherokee with the registration S556AJE was photographed returning to Adelaide on November 16.
A silver 2008 Nissan Pathfinder with the registration BB744S was seized on July 15 at Booborowie.
By mid-August, there had been 36 calls to Crime Stoppers about the case, which police said included some helpful information.
At the time, they said there would be a search for Mr Atkins' remains in the near future.
