Jacob Michael Smith was found guilty of murdering the woman while she slept next to two of her children in the living room of their Norman Park home on August 25, 2014.

After killing the woman, identified as Mandy in the Court of Appeal, Smith then brutally attacked her 12-year-old daughter.

Smith dragged the girl into a bedroom, telling her she was "gonna become a woman" and threatening to slit her throat if she tried to refuse.

After the rape, the girl said she would tell her mother with Smith replying: "okay, you do that" before fleeing the home.

The girl found her mother was already dead, with a "white sheet" that "wrapped around" her neck.

A panicked Smith fled the scene, texting friends for help, saying it was "an emergency".

He convinced a woman to collect him from Brisbane, telling her he had "done something stupid".

"I've killed someone. Didn't you see the news? It's all over the news," the court was told.

Police cornered Smith hiding in bushland at Gaven on the Gold Coast where he was taken into custody the day after the woman's death.

Smith did not testify at his 2018 trial and, on the 11th day of evidence, pleaded guilty to all of the charges except for the charge of murder.

Defence lawyers appealed the murder conviction, saying the judge erred by failing to sever the count of murder from the other charges.

In the decision handed down on Friday, Queensland's Court of Appeal found the judge also failed to instruct the jury that Smith may not have intended to kill the woman.

"It was material to draw the jury's attention to the not unreasonable possibility that the appellant fled from the scene and tried to evade police because of his sense of culpability for the unlawful and unintentional killing of Mandy caused by his intentional choking of her," the appeal court found.

Smith's murder conviction has been set aside, and he will be retried at a date to be set.

Australian Associated Press