A West Australian woman who smothered her 71-year-old mother with a cushion in the bedroom of her Tasmanian home has lost an appeal against her murder conviction.
Natalie Maher was found guilty in 2021 of killing Veronica Corstorphine in October 2019 and jailed for a maximum of 23 years.
Maher had been living with Ms Corstorphine in Launceston for about two months when tensions in their relationship re-emerged.
Maher was motivated by a "long-held personal antagonism" towards her mother and committed the crime through loss of self-control and perhaps inflamed by alcohol consumption.
The body of Ms Corstorphine, who has been remembered as phenomenally clever and kind, was found almost four weeks after her death on October 3.
Maher flew to Perth via Melbourne two days later after transferring $12,000 out of her mother's bank account. She was also found with jewellery belonging to Ms Corstorphine.
Tasmania's Court of Criminal Appeal on Tuesday dismissed Maher's appeal, with two of three judges ruling against her.
Maher claimed video of a police interview with her should not have been admitted as evidence at the trial because elements of the interrogation were "oppressive".
Justice Stephen Estcourt, one of the two judges to dismiss the appeal, said it was not unfair or improper for police to undertake the interview and ask questions even though Maher had indicated she had obtained advice not to comment.
"The police had a duty to investigate an allegation of a crime of considerable gravity," Justice Estcourt wrote.
"They were entitled to test the responses of the accused and to do so persistently."
Maher also argued the evidence of forensic pathologist Donald Ritchey should not have been permitted at the trial.
Dr Ritchey gave evidence that his clinical finding was the cause of death was undetermined due to decomposition.
He also said circumstances at the scene were highly suggestive of a homicide, evidence Justice Gregory Geason described as prejudicial because there was a risk the jury would use the information as a "shortcut" to the conclusion of foul play.
Justice Geason ruled Maher's conviction appeal should be allowed and it would be appropriate to order a retrial.
Maher will be eligible for parole in November 2032.
