A judge erred in sentencing mushroom cook murderer Erin Patterson as evidence she will be held in solitary confinement for years to come is lacking, prosecutors say.

Justice Christopher Beale handed Patterson, 51, a term of life in prison with a non-parole period of 33 years on September 8, for her murder of three members of her estranged husband's family, and attempted murder of a fourth.

A jury found her guilty on all counts, after she deliberately poisoned Don and Gail Patterson, and Heather and Ian Wilkinson, with a toxic beef Wellington lunch in July 2023.

Victoria's Director of Public Prosecutions formally lodged an appeal against Patterson's 33-year minimum prison term on Monday and the grounds for appeal were released on Thursday.

Acting Director of Public Prosecutions, Diana P

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