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

An alleged murderer testifying as a witness in their own defence is a rare strategy and normally a last resort.

Australian woman Erin Patterson has been found guilty of murdering three of her relatives and attempting to murder a fourth by serving them a meal laced with deadly death-cap mushrooms. The meal, a beef Wellington served at her home in Leongatha,