Erin Patterson's conviction for the deaths by poisoning of her estranged husband's relatives has prompted fevered speculation across Australia about her motive.

The Australian woman was convicted of murdering three elderly relatives of her estranged husband with a meal laced with poisonous mushrooms, and attempting to murder a fourth, in a case that gripped the country.

Emergency doctor tried to get mushroom cook to stay at hospital for treatment but Erin Patterson left, despite seeing her severely ill in-laws.