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

The mother-of-two was this week found guilty of deliberately murdering three people by using a beef wellington laced with death cap mushrooms.

An Australian woman was on Monday convicted of murdering three elderly relatives of her estranged husband with a meal laced with poisonous mushrooms, in a case that has gripped the country.