Walter Bolton, a 68-year-old Whanganui farmer, became the last person executed on 18 February 1957 in New Zealand. Convicted for the murder of his wife, Beatrice, he was hanged at Mt Eden prison following a controversial trial. Beatrice’s tea had contained traces of arsenic, and, over the best part of a year, she had consumed enough to kill her. Investigators found traces of arsenic in water on the Boltons’ farm, and in Walter and one of his…