The murders of Phyllis Harrison in 1998, Beverley Hanley in 2010 and Stephen Newton, whose badly decomposed body was found in 2011, have been the subject of Task Force Resolute, established after fresh forensic evidence was uncovered.

“We now have proof that the same offender is responsible for all three deaths,” Detective Superintendent Des Bray said today.

The involvement of a single suspect had been considered before, but was not able to be fully proven until now.

“There has been speculation in the past that the same offender was involved, but now I can say we have proof and we believe theft was the motive in all three matters,” Bray said.

Police would like to speak to witnesses again and have urged them to come forward.

“We know that there are people who have provided incorrect or incomplete statements and I would urge them to come forward and speak with us,” Bray said.

SA Police descriptions of the murders

Phyllis May Harrison

The 71-year-old was founded dead in her home in Harvey Rd, Elizabeth South on Tuesday 3 March 1998. She had suffered multiple stab wounds.

Her house was ransacked, but it is unclear what was stolen.

Beverley Ellen Hanley

The body of the 64-year-old was found at her home address in Homington Rd, Elizabeth North on Wednesday 6 October 2010 and she is believed to have been killed earlier that day.

She had suffered severe head injuries, her house ransacked and her handbag stolen.

Stephen Hugh Newton

The decomposing body of the 55-year-old was found in his home on Davison St, Mount Gambier on Friday November 4, 2011. He died as a result of an assault.

A range of items including a TV, DVDs, a computer game console, and games were taken.

Police believe it is more likely that he was killed sometime between 23 and 29 September but not found until 4 November.

– with AAP