The first Queensland man to challenge his murder conviction after his case was caught up in the state's forensic lab bungle says he should be granted an appeal after "dramatic" changes to DNA were uncovered in a review.
Andrew John Cobby was found guilty of murdering Kym Cobby at a Supreme Court trial in Brisbane in November 2021.
The jury accepted he attacked the 51-year-old, who he had been separated from at the time, with a hammer in 2017, before choking her to death outside her Gold Coast home.
During the trial, the court heard Cobby had been with Ms Cobby when she was killed but he was adamant a random man was responsible.
A forensic scientist testified in front of the jury that three sets of DNA, including the pair and a third unknown contributor, had been found on the hammer.
The following year, Cobby's case was automatically reviewed by Queensland Health Forensic and Scientific Services (QHFSS), after a commission of inquiry uncovered a litany of serious problems within the lab, including unreliable DNA testing methods.
After retesting of the hammer used in his case returned different results, Cobby launched an appeal on several grounds, including the fresh evidence.
Cobby also claims the verdict was unreasonable and there had been "repeated miscarriages of justice".
'A significant change'
On Tuesday, Cobby, who is representing himself, told the Court of Appeal the new DNA results showed "dramatic" differences from those presented to the jury during his trial.
"There is a significant change in the forensic analysis," he said.
"Such information is highly pertinent and relevant and should have been taken into [the jury's] consideration".
The court heard QHFSS had now determined there was no longer a third person's DNA located on the hammer, and the likelihood of Ms Cobby's DNA being on the weapon had increased.
Other changes included specific people, including their son, being wholly excluded from having their DNA present when they previously had not, the court heard.
Every sample looked at again
Matthew Hunt from QHFSS was called to testify during the hearing and was asked to explain the variances.
Mr Hunt told the court there had been an overhaul in the way the lab was run, including no longer using a "cut-off threshold" method to determine if there was enough DNA to conduct further testing.
He said in the Cobby case, "full processing" of the hammer samples were done again, even though some were previously considered too low.
"I've looked at all of the available results … and done a holistic reassessment," he said.
"So, whether any advancements since [the trial] can improve the results."
The court heard the lab now uses more advanced technology, which meant testing capabilities were more sensitive and improved.
Mr Hunt told the court there had also been changes to the way they interpret the data after external expert consultation.
"It's a mixture of both lab work and interpretation work, but it encompasses the whole of the samples in the case," he said.
"So, every sample has been looked at again, just to make sure it is the best it could be."
Mr Hunt explained this new method of interpretation was applied during the retesting, which is why the number of possible contributors was revised from three to two.
"They haven't reached that level at which we're confident enough to take account of them," he said.
"In general, it means we may have overestimated the number of contributors, now we've dropped that down."
While cross examining Mr Hunt about the latest results, Cobby was cautioned by Court of Appeal President Debra Mullins several times, and was repeatedly directed to stop asking "just irrelevant" questions.
As part of his appeal, Cobby also argued there had been unreliable witnesses who gave "very, very inconsistent" evidence at trial which contained "inaccuracies".
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Opposing all of the grounds, Crown Prosecutor Philip McCarthy told the court the hammer was just one of a number of things the jury had to consider, including evidence that Cobby's DNA was found under Ms Cobby's fingernails had "remained unchanged".
Mr McCarthy told the court the judges should accept the verdict would still be the same.
"The evidence sufficiently supported the conviction," he said.
The decision to allow the appeal has been reserved.
Outside court, Ms Cobby's cousin Darren Hanson said Cobby's bid for an appeal had been "quite overwhelming" for the family.
"It doesn't really give them any further sense of closure to where they were when the trial verdict was handed down now some years ago," he said.
"They're pleased that it's just over today."
Mr Hanson said the family had faith in the justice system.
"We'll let justice prevail."
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