Erin Patterson was either a calculating poisoner or, as she claimed, an appalling cook who accidentally killed three of her in laws with a Beef Wellington lunch laced with toxic mushrooms. Six weeks into the triple murder trial of the Australian mum of two and we are still no nearer to finding a clear motive for bumping off her estranged husband's parents and an aunt. Was it disputed family finances, a failure to help with school fees? And, if guilty, how did she think she'd ever explain all the lunch gathering dying - except her? Broadcaster Martin Frizell and award winning emeritus Professor of Criminology David Wilson take a look under the pastry lid but also explore poisoners through the years. Done properly, is it the perfect murder method?