DES MOINES — An Iowa prosecutor says a man meticulously planned to kill his former girlfriend’s fiancé, but a defense attorney says mental illness and side effects from a medication caused his client to commit the slaying. The trial of 27-year-old David Moffitt, of Pleasant Hill, began with opening statements Tuesday in Polk County District Court. Moffitt’s charged with murder, accused of shooting 30-year-old Justin Michael in May 2014 in Grimes as Michael slept next to his fiancée, Angie Ver Huel.