Details about Mushroom cook Erin Patterson’s links to WA have emerged, with residents revealing the killer and her husband lived in the State for about two years.

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

While Patterson has been found guilty of cooking the deadly mushroom lunch that killed three of her relatives and left another seriously ill, the motive is still unclear. There may simply be none. "You might be wondering, 'What is the motive?'" said prosecutor Nanette Rogers SC when she spoke to the jury in the trial back in April.