The Court of Appeal has upheld the convictions of two people jailed in relation to the 2016 murder of Samantha Kelly in Kangaroo Flat.
Christine Lyons was found guilty of murder and attempted murder, and Ronald Lyons was found guilty of attempted murder and assisting an offender, in June 2018 after a Supreme Court trial that lasted for almost six weeks.
Both applied to the Court of Appeal in March to overturn their convictions.
Christine Lyons sought leave to appeal on the grounds that the verdicts were "unsafe and unsatisfactory", and the guilty verdict for the charge of murder was inconsistent with the acquittal of Ronald Lyons on that same charge.
Ronald Lyons submitted that his conviction for attempted murder was unreasonable or not supported by evidence.
Peter Arthur, Christine Lyons' then-partner, pleaded guilty in 2017 to the murder of Ms Kelly, and later gave evidence at the trials.
He received a discount on his sentence for doing so, but Christine Lyons and Ronald Lyons denied any involvement in Ms Kelly's murder or earlier attempts on her life.
Counsel for the pair argued that no jury could be satisfied beyond reasonable doubt of their guilt on the basis of Arthur's evidence, as he had lied and repeatedly changed his account of events.
Arthur initially told police Ms Kelly had left in the middle of the night, then later said he killed her in self-defence, before giving evidence that there was an agreement to kill her.
Lawyers for Christine Lyons and Ronald Lyons subumitted Arthur only implicated them in Ms Kelly's death when he realised his own plea hearing was not going well for him.
But the prosecution argued the evidence presented as a whole was enough to establish Christine Lyons was involved in a plot to kill Ms Kelly, in spite of the problems with Arthur's evidence.
Prosecutor Chris Boyce pointed to other evidence, including statements Christine Lyons made about wanting to have Ms Kelly killed and her changing the names of Ms Kelly's children.
Mr Boyce also submitted that the case against Ronald Lyons did not rest solely on Arthur's account and other evidence included him being a party to a request for himself and Christine Lyons to be made guardians of Ms Kelly's children.
Three Court of Appeal judges found the murder case against Christine Lyons was "a powerful one, irrespective of whether the jury accepted everything that Peter said regarding what occurred in the early hours of 23 January 2016".
"Further, once it is accepted, as it surely must be, that there was an overwhelming case against Christine on the charge of attempted murder, her conduct in that regard was powerfully supportive of her guilt of the murder itself," Justices Stephen McLeish, Karin Emerton and Mark Weinberg wrote in their judgment.
They also found the case against Ronald Lyons on the charge of attempted murder was strong enough for a jury to find him guilty.
Both were refused leave to appeal their convictions.
In 2018, Christine Lyons was jailed for a maximum of 30 years, while Ronald Lyons was sentenced to 12 and a half years' imprisonment, for their crimes.
Both were housemates of Ms Kelly, who was 39 years old and a mother of four young children when she was killed on or about January 23, 2016.
Arthur admitted to murdering Ms Kelly with a hammer in a unit at a Wesley Street property that he and the Lyonses shared with Ms Kelly and her children.
Christine Lyons orchestrated the plot to kill Ms Kelly because she wanted the woman's four children, as she could not have any of her own.
In the days before Ms Kelly died, Christine Lyons, Ronald Lyons and Arthur attempted to kill her with a cocktail of drugs they mixed into drinks, a number of which were medications prescribed to Christine Lyons.
After Arthur killed Ms Kelly, Ronald Lyons helped him remove the body from the unit.
Ms Kelly's body was left in a dry creek bed at Shelbourne, where it was discovered on February 12 when Arthur led police to the site.
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