It began as a family argument and ended in tragedy – a teenage girl stabbed to death by her elderly grandfather in a case that shocked a nation. In a court in western Japan last month, Susumu Tomizawa, 88, admitted to killing his granddaughter Tomomi, 16, nearly two years ago – but, he said, he doesn’t remember doing it. Tomizawa has Alzheimer’s, a progressive and irreversible neurological disorde