Brutal 1998 murder detailed in SA court

A South Australian man whose disappearance and murder went unsolved for 18 years was bludgeoned to death with a metal bar, a court has heard.

Adrian Mahoney, 67, has pleaded guilty to the murder of Dale McCauley at the victim's home at Wilunga, south of Adelaide, in January 1998.

In what was one of the state's most baffling cold cases, Mr McCauley's remains were only found in January last year, after Mahoney was arrested.

A video plea from the dead man's sister, which was shown to Mahoney in detention, prompted him to disclose the isolated location at Rapid Bay where he had dumped the body.

In sentencing submissions in the Supreme Court on Friday, prosecutor Carmen Matteo said the attack on Mr McCauley was "brutal" with Mahoney striking him multiple times in the head with a metal bar.

She said the killer had wielded the bar in two hands and had attacked from behind.

The murder was prompted by Mahoney's anger at a decision by the 44-year-old not to go ahead with a plan for the pair, who were friends at the time, to restore a boat and move to Queensland to start a business together.

Defence counsel Mark Griffin told the court Mahoney lost his temper and self-control for just a "minute or two" when he struck the victim causing the fatal injuries.

Mahoney was immediately "distraught and horrified" by what he had done but went about covering up the killing, the court heard.

In her victim impact statement, Mr McCauley's sister, Sandra Cole-Stokes, told the court he was a quiet person who loved the outdoors and was a follower of the Buddhist faith.

"After 18 years of waiting and wondering what happened to Dale and consoling our grieving parents, it came as a great shock that his remains had finally been found and police had a suspect in custody," she said.

Outside the court, Ms Cole-Stokes said she still couldn't understand how Mahoney could lie to her father and police after her brother's disappearance.

"I'm a little bit taken aback by the fact that a friend could not have dumped Dale and left him all those years and never have guilt enough to admit to it and to say this is where he is," she said.

"Just the thought of how far he drove to roll Dale's body down the bank and leave him there is just beyond me, it really is."

Justice Malcolm Blue will sentence Mahoney, who is now suffering prostate cancer, on a date to be fixed.