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 world has met Erin Patterson as the murderous cook behind a mushroom meal that killed three relatives. But years before her courtroom infamy, the woman from Melbourne's suburbs divided opinions.

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