Updated December 17, 2014 15:48:53

Photo: Dianne Rogan had been having an affair with her killer, the court was told. (Supplied)

A man has been found not guilty of murdering a Whyalla woman he was having an affair with, but he has been convicted of manslaughter.

The Supreme Court in South Australia heard Dianne Rogan, 52, was found naked next to her backyard spa bath with extensive injuries in July last year.

She and Bevan John Brougham, 53, had been having a sexual relationship but Brougham denied he murdered the woman.

The court heard Brougham was the son of Mrs Rogan's neighbours.

It was told the woman died after Brougham went to her home to have sex while her husband and son were away overseas.

Brougham claimed a fight erupted after he tried to end their relationship.

The prosecution told Justice John Sulan the woman died in a sustained and extremely violent attack, and most likely had refused Brougham's advances on the day she died.

Justice Sulan said he could not be satisfied Brougham intended killing Mrs Rogan or causing very serious harm, given he had consumed significant alcohol.

He said he could not exclude that Brougham might have tried to revive her, which would be inconsistent with murder.

There will be sentencing submissions next month.

Topics: courts-and-trials, murder-and-manslaughter, crime, prisons-and-punishment, law-crime-and-justice, whyalla-5600, sa, port-pirie-5540

First posted December 17, 2014 15:35:21