A nurse accused of murdering two elderly women in a nursing home on the New South Wales north coast had previously boasted about knowing how to kill a person without it being detected, a court heard. Registered nurse Megan Haines is accused of killing 82-year old Marie Darragh and 77-year-old Isabella Spencer. It has been alleged she injected both with fatal doses of insulin at Ballina’s St Andrews Village nursing home in May 2014. Her murder trial began in the Supreme Court at Lismore on Wednesday.