South Australian investigators have called in equipment from federal police as they continue their search for a man who was "walked into the scrub" before being killed in the state's mid-north.
Officers spent a second day searching for the remains of Adelaide man Robert Atkins in an area between Orroroo and Peterborough, with Australian Federal Police drones and ground-penetrating radar capabilities deployed.
Mr Atkins is thought to have been murdered due to his links to the drug trade. He is one of three men believed to have been killed by the same group, described as low-level drug dealers and petty criminals.
Police believe the clothes Mr Atkins was wearing when he was last seen alive, committing an offence in Port Adelaide in November 2020, will be found in their search.
"We believe Robert was wearing those clothes at the time of his death and that those clothes and shoes will be located somewhere in this area," Detective Superintendent Des Bray said on Wednesday.
Det Supt Bray added it was "difficult to know" whether anyone attempted to conceal the body later, due to the laziness of the offenders.
"We're talking about lazy people ...They're drug dealers because they don't want to work," Det Supt Bray said.
"We expect he's probably bought him out here, stopped the car, walked him into the scrub and killed him. And that's the information we have to hand.
"We're very confident that the offender was back in this area several days later, very close to where we stand now."
Det Supt Bray did not comment on how police knew the body had not been removed when the offender returned to the area. Officers have covered between four and six square kilometres of area in their search, doubling that of Tuesday's efforts.
There is a $200,000 reward for information leading to the conviction of the people responsible, with the same amount on offer for information leading to the discovery of Mr Atkins' body.
Det Supt Bray said every effort will be deployed to find the remains.
"It's very achievable if his body is in this area to find it," he said.
"We'll do whatever we can to try and find Robert's remains for his family."