Detectives and emergency services converged in Adelaide Hills on Tuesday morning to search nearly 30km of road on foot, after receiving new information Mr Purse's body had been driven to the area.

"We're hoping to find Michael's remains, but there may be discarded clothing that a farmer or property owner might previously have not considered relevant to the investigation ... we'd really like those people to come forward and it may actually narrow down the search area for us," Detective Inspector Brett Featherby said.

Mr Purse was last seen in February 2019 when he was collected from the Adelaide Casino and taken to a unit at suburban Kilburn.

It's there police believe he was murdered the following morning, with his body placed in the boot of a car and eventually disposed.

His disappearance was declared a major crime and three men were arrested in 2021.

Previous searches north of Adelaide had failed to find his remains or the weapons used to kill him.

Det Insp Featherby said he believed Mr Purse's body had been buried near Balaklava in a shallow grave.

He acknowledged the difficulties of the search.

"There have been four years passed since Michael was buried at this location," he said.

"We've had changes in vegetation, there have been environmental changes, there have been roadworks - and obviously the size of the area to search is considerable."

Police will continue their search for four days.

Australian Associated Press