A police interview conducted eight days before alleged serial killer Steven Leslie Hainsworth was arrested for the murder of his aunt has revealed that his DNA was found at the scene of the crime.

Mr Hainsworth, 49, is standing trial in South Australia's Supreme Court charged with the murder of his aunt Beverley Hanley in 2010, 55-year-old Stephen Newton in 2011 and 77-year-old Phyllis Harrison in 1998.

The almost five-hour video interview, released exclusively to the ABC, shows Mr Hainsworth being questioned about Ms Hanley's murder by two major crime detectives at Loddon Prison in central Victoria on May 8, 2019.

Eight days later, on May 16, police charged Mr Hainsworth with murder and sought his extradition to South Australia.

He was subsequently charged with Mr Newton's murder on November 21, 2019, and Ms Harrison's murder on June 25, 2020.

Prosecutors previously told the court that Ms Hanley died as a result of suffering "blunt and sharp force trauma" on October 6, 2010, before her home was ransacked and several items, including a camera and jewellery, were stolen.

In the 2019 interview, police tell Mr Hainsworth his DNA had been found on a phone cable at Ms Hanley's home and that his aunt's DNA was found on a camera he pawned at Cash Converters in Elizabeth soon after her death.

"I put it to you that, this is the case because you did kill Beverley Hanley that day," a detective says.

"No, I don't believe I did. I don't believe I did," Mr Hainsworth responds.

"Well, I didn't. I didn't. The phone thing that's no guarantees, that, the rings are iffy, and the camera … you said it's got her DNA on it, but I just can't work it out, like, if that's the case, why hasn't, I mean, someone come and seen me before?"

In the interview, the detective tells the then-44-year-old that the phone cord at Ms Hanley's house was pulled out of the wall.

"An examination was done of that cord, your DNA was located on that cord," the detective says.

"Allegedly," Mr Hainsworth responds.

The detective continues to detail that police have evidence proving Mr Hainsworth pawned a distinctive three-set-cluster ring set belonging to Ms Hanley four hours after her death.

Earlier in the interview, detectives question Mr Hainsworth about how he came to be in possession of the Kodak camera that was found to have Ms Hanley's DNA on it.

"So, it's been given to scientists to examine. Beverley's DNA is on that camera, which then shows, or corroborates, that that is her camera," the detective says.

"No. I find that hard to believe it's the same ring as well," Mr Hainsworth responds.

The detectives also probe Mr Hainsworth about reports a friend had seen him wearing blood-stained clothing the morning of Ms Hanley's murder.

"He's said that at about nine o'clock in the morning, so this is the morning Bev was killed … you have knocked on the door of his house … [and] you've said to Volley that you need a change of clothes, that you need some new shoes," a detective says.

"While he's talking to you, he's seen what he thinks is blood on your pants."

Mr Hainsworth denied ever being at his friend's house on the morning of his aunt's death.

In the interview, he agrees police seized his blood-stained clothing the following day.

"And you said 'they were clothes that I was wearing all day the day before'," the detective asks.

"Yeah," Mr Hainsworth responds.

"The day that Bev was killed," the detective confirms.

The trial before Justice Adam Kimber, without a jury, continues.