The defence in a euthanasia trial has cast doubt on the accuracy of the accused's book, calling parts of it fiction.
Sean Davison is on trial at the High Court in Dunedin for the attempted murder of his terminally-ill mother, Patricia Davison, in 2006.
Mr Davison wrote about his mother's death in a book Before We Say Goodbye, and in early drafts described giving her a cocktail of crushed morphine tablets to hasten the end.
His mother's GP, Peter Borrie, told the court he was very surprised by a draft he saw, and insisted on changes to the parts that referred to him.
Professor Davison's lawyer, Roger Laybourn, used this to question the book's account, describing parts of it as sensationalist and fiction.
Several health professionals called as witnesses agreed Mr Davison appeared to have overstated his involvement in his mother's death.
Earlier, Dr Borrie told the court Mrs Davison asked him to speed up her death.
Dr Borrie told the court that as her cancer advanced she often said she wanted to hasten her death, suggesting she would throw herself into the harbour or swallow a bottle of pills.
He said Dr Davison once asked him if he could give her a syringe of morphine, but he refused, saying euthanasia was illegal in New Zealand.
Dr Borrie said at that the time of Dr Davison's death he believed she had died from the cancer or its complications, and found out only years later there was more to the story.