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

Patterson fed her former in-laws beef Wellingtons laced with poisonous death cap mushrooms, the jury’s verdict said.

An Australian woman was on Monday 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.