Lawyers for Thomas Chris Lang, who was convicted twice for murdering socialite Maureen Boyce in her Brisbane apartment in 2015, made arguments in the High Court on Friday arguing for the conviction to be quashed.
Lang, who was first found guilty in 2017 before the sentence was quashed on appeal, was convicted for the crime again in November 2020 following a retrial and sentenced to life behind bars.
Lawyers for Lang unsuccessfully tried to appeal the second conviction in the Queensland Supreme Court, before leave was granted in November 2022 to have the case heard in front of the High Court.
The court was told the case against Lang was largely circumstantial due to there being a reasonable possibility Ms Boyce had died by suicide, describing the case as a "miscarriage of justice".
Ms Boyce, a former fashion model, had been stabbed five times in her bed with a kitchen knife with such force that the blade had pierced the blood-stained bedding three times.
The pair had known each other for 30 years and had rekindled an earlier relationship.
The jury in the second murder trial had found Lang had stabbed Ms Boyce in a jealous rage after he read text messages between her and another man.
However, lawyers for Lang have stated Ms Boyce died by suicide after going to her bedroom in a depressed state.
They have argued there was no blood or DNA from Lang found on the knife and that there was no blood in any other location in the apartment other than the bed.
The court was told the crime scene had no sign of a struggle and that Ms Boyce would have been able to fight off an attacker.
Lawyers for Lang told the court it would have "defied credulity" that Ms Boyce would not have been able to have woken up and be able to fight off an assailant, with the amount of alcohol and medication in her system at the time of the incident unlikely to have prevented a fight response.
Central to Lang's appeal case is the testimony given at the second trial by a forensic pathologist, which Lang's legal team says was allowed to state an opinion that the fatal wound was more likely to be have been caused by another person, rather than being self-inflicted.
Lang's lawyers told the court the forensic pathologist had provided a personal opinion, rather than an expert view as to whether the stab wounds had been from suicide.
But crown lawyers said the pathologist had only commented on the wounds being unlikely to be self-inflicted due to his experience from previous cases, saying it would have struck them as odd and the remarks were based on physical observations.
They also argued Ms Boyce's arthritis would also have prevented her from inflicting the stab wound herself, and that while she had been depressed, it was not indicative whether it would lead to suicide.
The Crown also argued Lang had lied about the circumstances about Ms Boyce's phone being thrown from the apartment balcony, saying that "the truth was damning".
While Lang had previously claimed Ms Boyce had thrown the phone from the balcony on the night before she died, prosecutors said the phone had been unlocked prior to her death and was thrown away.
The court has reserved its decision, to be handed down at a later date.
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