The two friends believed they could stay together if Pauline's mother would let her leave New Zealand. Some felt it was a curious friendship for Hulme, whose family were well to do, her mother glamorous and clever. She turned to her close friend, Parker, a working-class girl from a humble background. The shock to Hulme - who had not been at school because of tuberculosis, from which she had suffered since the age of 13 - was cataclysmic. At the same time, her father lost his job and she was to be sent to South Africa to stay with an aunt. Three days before she took part in the killing of Honora Parker on June 22, her parents announced that they were to divorce - triggered by Hulme having found her mother, Hilda, in bed with a lover. In 1954, Hulme felt as if she had been pushed to the limit. I wanted to explore what people will do when faced with experiences and inner conflicts that test them to the limit.' This series - more literary and epic in scope than her pacy earlier novels - will look at personal morality 'against the background of that five years of war when things were so changed for men and women. 'It is vital for me to go on exploring moral matters,' she says.

Perry's books grapple with questions of sin and repentence, the price of redemption and forgiveness. When it appeared in the US, it topped the New York Times bestseller list. Her new novel, No Graves As Yet, is the first of a five-part series centred on the first world war. In the past four decades, Perry has published 40 books and established herself as a leading crime novelist, selling more than 10m copies. She became a Mormon and moved to a small, secluded community in Scotland. 'I had to give up my past - the hardest thing imaginable - and begin life in my new identity as Anne Perry, knowing even a tiny slip could unravel everything,' she says. She was released from prison in 1959 and set about reconstructing her life. The grisly story was the subject of Peter Jackson's film Heavenly Creatures, in which Hulme was played by Kate Winslet.

Both were convicted of murder and sent to prison. In 1954, Perry - then a 15-year-old called Juliet Hulme, living in New Zealand - helped to bludgeon to death the mother of her friend, Pauline Parker. Sometimes the past casts too long a shadow. 'W hy can't I be judged for who I am now, not what I was then?' asks the novelist Anne Perry.

All About Redemption by Kathleen Reagan