A woman in Australia was sentenced on Monday to life imprisonment for murdering three of her husband’s relatives and trying to murder a fourth by serving them beef Wellington laced with poisonous mushrooms.

The woman, Erin Patterson, 50, was convicted of the crimes in July after a two-month trial that captivated the nation. She will not be eligible for parole for more than three decades.

Prosecutors said that she had meticulously planned the poisonings, misled the authorities and attempted to conceal evidence. They argued that the crimes were so horrific that she deserved the highest possible sentence and should not be eligible for parole.

In his sentencing remarks, Justice Christopher Beale of the Supreme Court of Victoria said that Ms. Patterson’s offenses involved “substantial premeditation” and were followed by an “elaborate cover-up” of her guilt.

Addressing Ms. Patterson, he said, “Your failure to exhibit any remorse poured salt into all of the victims’ wounds.”

At the center of the case was a lunch that Ms. Patterson hosted more than two years ago at her home in Leongatha, a rural town in the state of Victoria. She had invited Simon Patterson, her estranged husband, but he declined. In attendance were his parents, Gail and Don Patterson, along with Gail’s sister, Heather Wilkinson, and her husband, Ian Wilkinson.