Patterson

The Supreme Court trial of Erin Patterson, 50, began in the small Victorian town of Morwell on Wednesday and is expected to last six weeks.

Ms Patterson has pleaded not guilty and her defence team says she "panicked" after unintentionally serving poison to family members she loved.

Three people died in hospital in the days after the meal, including Ms Patterson's former in-laws, Don Patterson, 70, and Gail Patterson, 70, as well as Gail's sister, Heather Wilkinson, 66.

But she alleges Ms Patterson "deliberately poisoned" her guests "with murderous intent", after after inviting them for lunch "on the pretence she'd been diagnosed with cancer".

Dr Rogers said the jury would hear evidence that Ms Patterson had travelled to a location, near her home in Leongatha, where death cap mushroom sightings had been logged on a naturalist website.