A man who murdered his wife in a “cowardly rage” by striking her from behind with a 1.8kg sledgehammer has failed to overturn his conviction on appeal.

Shaun Robert Sturgess, then aged 54, had pleaded guilty to the manslaughter of his wife of 17 years, Jacqueline, at the start of his Queensland Supreme Court trial in February 2024.

In April 2020 police found his wife face-down in a pool of blood in the house the separated couple had formerly shared at Narangba, north of Brisbane.

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Prosecutor Chris Cook refused to accept that plea and the charge of either murder or manslaughter was put before a jury, which later returned a guilty verdict for murder.

Three judges in the Queensland Court of Appeal on Tuesday handed down their unanimous judgment to dismiss Sturgess’ appeal against conviction.

Defence barrister Saul Holt had told the judges at a hearing in April that Sturgess had three grounds for appeal, including that the jury being told of an earlier episode of violence in the relationship had caused a miscarriage of justice.

Holt also submitted that the jury were not properly warned by the trial judge against relying on hearsay evidence and not properly instructed on the element of intent that the prosecution had to prove.

The prosecution had not argued at trial that Sturgess committed premeditated murder but rather had struck his wife with a single blow of severe force and in that moment he had the intention to kill or at least do her grievous bodily harm

Holt said Sturgess had struck his wife in an “uncontrolled rage”, either devoid of any thought process at all, or at least without a murderous intent.

Justice Soraya Ryan found Sturgess’ prior violent incidents were “relevant background” in the case and there was no miscarriage of justice.

“And even if I am wrong about that ... any such wrong decision could not realistically have affected the reasoning of the jury to their verdict of guilty of murder,” she said.

The appeal justices listed the numerous statements Sturgess made to police and in letters after his wife’s death that were shown to the jury to prove intent.

“She’s probably driven me to it. But she didn’t deserve that,” Sturgess told police in an interview.

Sturgess was sentenced to life imprisonment in February 2024 with a mandatory 20 years without parole, reduced to 16 years and two months due to time already served.

Cook said Sturgess had struck his wife with significant force out of a sense of “cowardly rage” as part of a horrible domestic violence incident.

In sentencing, Justice Tom Sullivan said Sturgess had left the scene to buy and drink alcohol without checking his wife’s vital signs.

“In your police interview there is a sense of regret, a lot in respect of yourself, some of it wallowing in self-pity,” Justice Sullivan said.

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