A US doctor's murder conviction over his socialite lover's stabbing death in her Brisbane penthouse amid a jealous rage has been overturned on appeal.
Thomas Chris Lang was found guilty in December 2017 and sentenced to life in prison after Maureen Boyce was found with the knife so deeply embedded in her abdomen part of the handle was inside her body.
He will be retried after his conviction was quashed by the Court of Appeal on Friday citing the "real possibility that irrelevant but misleading evidence was used to convict the defendant".
Lang's Supreme Court trial heard Ms Boyce's death was either a suicide or a homicide perpetrated by the doctor.
Prosecutors told the jury Lang had sought revenge after finding evidence on Ms Boyce's phone that she had been communicating with a man he suspected her of being romantically interested in.
One expert witness said the direction of blade tracks, the absence of blood on the deceased's dominant hand and that the stabbing was through a sheet pointed to the involvement of a second person.
The prosecution also submitted medical evidence about the dead woman's mental health, saying she suffered from bipolar disorder, as well as statistical data about the suicide rates of Australian women.
"The evidence indicated that a female - regardless of age, ethnicity, socio-economic level or other considerations - was very unlikely to commit suicide, even if suffering from a bipolar disorder," a full bench of the court said in its reasons.
At his appeal, Lang's lawyers argued the suicide data was irrelevant and misleading and and should never have been admitted.
They said it was not useful to the jury in determining whether Ms Boyce had suicided by stabbing and may have caused the jury to more readily discount the possibility of suicide.
Appeal judges Justices Philip McMurdo, Robert Gotterson and Anthe Philippides agreed, saying it had "no significance".
"The jury was not warned against reasoning in a way that is sometimes called "the prosecutor's fallacy", they said in their reasons.
"Namely, that because suicide is rare in the general population and stabbing is rare as a means of suicide, the deceased is more likely to have died by homicide than by suicide."