Man arrested over 2011 South Aust murder

A man has been arrested over the 2011 cold case murder of Mount Gambier man Stephen Hugh Newton.

Mr Newton's decomposing body was found inside his home, while a TV, DVDs, a computer games console and games had been taken from the property.

The 55-year-old had been assaulted prior to his death.

Police believe it is likely he was killed sometime in September although his body was not found until November.

A 45-year-old man was arrested on Thursday as part of SAPOL's Operation Persist, which has used a range of strategies to review unsolved murder cases.

He is expected to be charged with murder and appear in the Adelaide Magistrates Court on Friday.

Detective Superintendent Des Bray, the officer in charge of Major Crime, said police were limited in what they could say because the matter is now before the courts.

"However, I would like to reiterate that SA Police never consider unsolved matters such as this 'closed'," he said.

"Even though matters may not be in the public eye, we continue looking for fresh lines of inquiry in a bid to bring offenders to justice."