Erin Patterson, 50, was in July convicted of three murders and one attempted murder over a death cap mushroom-laced beef Wellington she served to her estranged husband's family.
A jury found her guilty following a near-11 week trial in the regional Victorian town of Morwell.
Patterson will face the Supreme Court in Melbourne for a pre-sentence hearing, where sole surviving victim Ian Wilkinson and family of her murder victims are expected to give statements.
The Pattersons and Wilkinsons, who attended much of the trial, have not been seen in court since before the jury returned verdicts on July 7.
Their victim impact statements will either be read out by them, or a prosecutor, at Monday's plea hearing.
Prosecutors will argue how long Patterson should be jailed for over the murders and attempted murder and her defence team will explain any factors that should mitigate the length of her sentence.
Patterson deliberately served up the poisoned dish during lunch at her Leongatha home in 2023, to her former mother and father-in-law, Don and Gail Patterson, Gail's sister Heather Wilkinson and her husband Ian.
Her lunch guests were taken to hospital, with Don, Gail and Heather dying days after the meal.
She invited her estranged husband Simon to the deadly gathering, but he declined the night before.
Jurors were not told the reason he did not attend, with that information revealed weeks later after a suppression order was lifted.
Justice Christopher Beale allowed pre-trial evidence to be released for the first time.
Simon allegedly believed Patterson had been trying to kill him by poisoning meals since 2021, during or before camping trips the pair took together.
He claimed Patterson poisoned him with a penne, chicken curry and a wrap she had prepared, but she denied this and the allegations were never tested at trial.
She was charged with three counts of attempted murder, but they were dropped at the start of her trial after Justice Beale ruled they should be heard separately.
Other evidence ruled out of trial included an allegedly fake cat post to a poisoning help page, an appendix from a Criminal Poisonings book allegedly found on a tablet and an additional trip to the tip on the day of the lunch.
Patterson will be brought in person from prison to the plea hearing, which is expected to span two days.
She faces life in prison and a date for her sentence could be set at the hearing.
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