Man denies he is SA triple-murderer

SA detectives have a prime suspect in three murders, but a Victorian man says he is innocent

A Victorian man who is the prime suspect in three separate cold-case murders in South Australia says he is innocent.

Steven Hainsworth, who now lives in Mildura, has admitted detectives have linked him to the murders of two grandmothers and a pensioner over a 13-year period through new forensic evidence, but has denied killing anyone.

"I've been told I'm a suspect in the crime, but I haven't done anything. Nothing. I'm not a serial killer. I haven't killed no-one. I've had fights in my life and I've got hurt, as you can see now. I'm not responsible for no-one's murder," Mr Hainsworth told the Nine Network on Thursday.

"I hope that whoever is responsible is caught and then I've got the monkey off my back."

On Tuesday, South Australian police said they had uncovered fresh forensic evidence that linked the three murders for the first time.

"Now I can say we have proof and we believe theft was the motive in all three matters," Detective Superintendent Des Bray said.

The involvement of a single suspect had been considered before, but was not able to be fully proven until Task Force Resolute initiated a review into the cases earlier this year.

Phyllis Harrison, 71, was found dead with multiple stab wounds and her Elizabeth South home ransacked in 1998, while 64-year-old Beverley Hanley suffered severe head injuries and her handbag was stolen from her Elizabeth North property in 2010.

A range of items including a TV, DVDs and computer games were missing from Stephen Newtown's Mount Gambier unit after he was found dead and covered in rubbish in 2011.

"This was a cowardly attack on two grandmothers and an invalid pensioner; each attack was extremely brutal," Supt Bray said.