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

A doctor who treated some of the victims of the 'mushroom murderer' explains the moment he realised Erin Patterson committed the deadly crime.

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.