Andrew Cobby appeals guilty verdict after jury found he murdered his estranged wife Kym

A man convicted over the murder of his ex-wife has admitted he didn’t properly understand key forensic evidence he was using to prove his innocence, a court has been told.

A man who found guilty of the murder of his estranged wife has questioned a forensic expert about the retesting of the hammer used to kill the 51-year-old outside her Gold Coast home as he seeks to have his conviction overturned.

Kym Cobby’s body was discovered moments after she was attacked on the side of the road by a family member outside her Worongary property in November 2017.

Andrew John Cobby was found guilty of killing Mrs Cobby after a jury heard he had beat the mother of three with a hammer owned by his roommate.

Cobby had also strangled his ex-wife before fleeing into the bushland, where he was later found by police.

Cobby has always maintained the pair had been attacked by a random man and that he left the scene fearing for his life.

In 2022, Cobby was granted an appeal after a Commission of Inquiry into the Queensland’s DNA lab found widespread failings across many criminal cases, including samples being reported as having no or insufficient DNA for testing.

Kym Cobby was killed by her estranged husband, Andrew, in 2017.

Andrew Cobby was laying on the ground when found by police. Picture: Supplied / QLD Police

Cobby, who is self represented in his appeal, has previously argued the retesting of the hammer used during the murder showed DNA of other unknown people.

As the appeal came before the court on Tuesday, Cobby cross-examined Matthew Hunt of Queensland Health Forensic and Scientific Services, who had conducted the reanalysis of the hammer.

Cobby questioned Mr Hunt about how new technology being used by the lab is “producing a different forensic DNA analysis which totally changes the original interpretation” presented to the jury.

Mr Hunt told the court changes in results were likely to occur because of the way the system now operates.

He explained the way new testing is done meant forensic analysis only focused above a certain DNA threshold, compared to the previous method which would look at additional contributors below the threshold and include those in the overall results.

Mr Hunt said the lab now uses a new way to analyse DNA that is “more sensitive” compared to how the process was done before the inquiry.

“It’s not to say at the time the interpretation was flawed in any way, at the time it was the best interpretation that was available to us,” Mr Hunt said, referring to how the lab previously tested DNA.

The hammer Andrew Cobby used to attack Kym Cobby was retested to analyse the DNA found on it. Picture: Supplied / QLD Police

“There are a number of changes that have been made through the inquiry … (which) change the way we interpret things.”

“It’s unlikely these results would change in a significant way.

“Every time you runs the analysis, it does always provide different (results).

“You can’t always get the same numbers.”

The court heard further retesting of the DNA found on the hammer had determined there were two DNA “contributors”, compared to a previous determination that there had been three contributors.

Cobby previously told the court he’d only received the latest report from the QHFSS about seven days ago.

The court was told four new reports had been done since the trial.

On several occasions, Court of Appeal President Debra Mullins told Cobby she wouldn’t allow him to follow several lines of questioning he had hoped to follow with Mr Hunt.

She said Cobby was repeating himself unnecessarily through his cross-examination after Mr Hunt had already “covered” several issues in his evidence.

Cobby told the court Mr Hunt’s “explanation” of how the retesting worked “cleared up some of the misconceptions” he had about the forensic reports.

Despite this acceptance, Cobby told the court he still wished to continue with his six grounds of appeal.

Cobby argued there was an unreasonable verdict made by the jury as well as five instances of a “miscarriage of justices repeated during the trial”.

Supporters and family of slain woman Kym Cobby said sitting through the appeal process has been ‘difficult’. Picture: NewsWire / Glenn Campbell

Crown Prosecutor Philip McCarthy told the court the new DNA evidence would still lead a jury to a guilty verdict.

“(The hammer) was one strand among 13 strands in the Crown’s case,” Mr McCarthy said.

“It wasn’t a link in the chain.”

Mr McCarthy said the jury had been given an explanation as to why certain “DNA may or may not be deposited on the hammer”.

“It was clear the hammer was used on Mrs Cobby and her DNA was not on the hammer,” he said.

The court heard Mr McCarthy said Mrs Cobby’s DNA was still found under Cobby’s fingernails, as was his under hers during testing.

The 51-year-old woman’s blood was also stained on Cobby’s clothes, the court was told.

The Court of Appeal has reserved its decision to a later date.

Mrs Cobby’s cousin, Darren Hanson, told reporters outside of court Tuesday’s hearing had been a “difficult day for everyone”.

“It’s been quite overwhelming,” he said.

“It’s been a long day for them, it doesn’t really give them any further sense of closure to where the trial verdict was handed down several years ago.

“It’s something the family has had to go through and they’re pleased that it’s just over today.

“We’ve got faith in the justice system and we’ll let justice prevail.”

Originally published as Andrew Cobby appeals guilty verdict after jury found he murdered his estranged wife Kym