One of Your Own: The Life and Death of Myra Hindley by Carol Ann Lee

May she rot in hell the headlines screamed when Myra Hindley died in November 2002. Yet even the prospect that the Moors Murderess is now enduring eternal damnation in the firey pit doesn't seem to have caused the memory of her and her crimes to burn any less fiercely in the public imagination. Since her death, there have been several 'personal' accounts published, purporting to reveal what she was really like (often by those who scarcely knew her), two prize-winning TV dramas starring Maxine Peake and Samantha Morton, and now there is Carol Ann Lee's biography. Hindley, it seems, continues to intrigue us from beyond the grave every bit as much as she did during her long incarceration for her part, alongside her lover Ian Brady, in the murder of five youngsters in and around Manchester between 1963 and 1966.

I say 'us' advisedly. I worked as a consultant on one of those TV dramas which was based, in part, on my biography of Hindley's most enduring and most reviled champion, the former Labour cabinet minister and lifelong prison reformer, Lord Longford. And I was interviewed by Lee whose questions caused me to re-examine memories of visits and correspondence I had with Hindley in the 1980s and 1990s. Not for the first time, I found myself struggling to offer any plausible explanation as to why the intelligent, engaging, remorseful and profoundly religious woman I met back then could also have been the unfeeling, perverted monster who had committed such appalling acts of violence.

We don't like the inexplicable. It makes us feel uncomfortable and insecure. Science has been telling us for centuries that there is an answer for everything, so when we can't find one that satisfies us, our fascination tends to grow rather than diminish. It is particularly true when faced with horrific crimes. The same process was at work recently in the outcry over the recall to prison of Jon Venables, one of the two youngsters who in 1993 brutally murdered James Bulger. Many have picked over the short lives of Venables and his partner in crime, Robert Thompson, looking for clues as to why they turned into murderers one February day in a Bootle shopping centre. Yet no-one has so far quite managed to come up with an explanation that satisfies public incomprehension at the unthinkable reality of two 10-year-olds torturing a toddler and leaving his mutilated body on a railway line.

With both Hindley and James Bulger's killers, our confusion tends to cause us to reach for the word evil, usually with a full stop after it, as if delivering the final and most damning verdict possible. But what precisely do we mean by evil? Is it evil in the traditional Christian sense – possession by the Devil? Even most mainstream Anglicans and Catholics would balk at such a medieval formulation, not least because it absolves Hindley/Brady/Venables/Thompson of any responsibility for their actions. Or do we mean evil in the modern psychological sense – that each of us has within us the capacity to do good and evil but a tiny number choose the latter? Or do we simply mean evil in the sense that Hindley's crimes are, as another of her biographers, the Welsh dramatist Emlyn Williams, put it in the title of his celebrated 1968 account, 'beyond belief'?

Williams' book mixed fact and fiction to unravel the mystery of Hindley. Lee (whose previous work includes an acclaimed biography of Anne Frank, a figure at the other end of the good-bad spectrum of public judgements) is no less aware of the need to find a plausible answer. "It is," she writes, "an unbearable fact that Hindley was capable of love and kindness towards her family and friends, adoring of her niece and the children of those who visited her in prison, yet had been responsible for the sadistic murder of other children".

Yet her chosen methodology is to stick steadfastly to the facts. Indeed, one of her reasons for writing yet another account of Hindley, she says at the very start of this measured and self-consciously unsensational book, is to get the facts absolutely right for the first time. In pursuit of this, her research has clearly been exhaustive and she allows most of those involved with Hindley, her crimes and her 36-year campaign to win parole, the chance to offer both their account of events and their perspective.

The result is a rounded picture and a compelling read, not least because while Lee offers a series of clues and possibilities to Hindley's motivations and true nature, she ultimately leaves the reader to reach their own verdict. How did an apparently ordinary girl from Gorton in Manchester change into a gorgon who haunts our imagination to this day? How could the girl who was much in demand locally as a reliable and affectionate babysitter get involved in abusing and murdering children, even tape recording the final agonies of one of her victims, 10-year-old Lesley Ann Downey?

If Lee's approach sounds like, a cop out, think again. It requires considerable skill and clear-sightedness. Just as you are tempted to see a potential cause for her later actions in Hindley's unusual upbringing, with a drunken, abusive father, an unhappy, inconsistent mother and a doting grandmother with whom the young Myra lived in preference to her parents, Lee introduces another voice to put the opposite point of view. Such an upbringing was not that unusual for the time in poor families, struggling to survive. Her sister, Maureen, endured much the same situation and didn't turn out a cruel murderer.

Sometimes the counterpoint to easy explanations is offered by Hindley herself, who, as this biography shows all too often, was prone at different stages of her imprisonment to blame anyone and anything for what she had done in preference to herself, but at others dismissed all attempts by her supporters to make excuses for her.

Even on the key question of who influenced who – was Hindley put under a spell by Ian Brady (who Longford always described as 'brilliant but bonkers'), or did she egg him on to turn his homicidal dreams into terrible reality? – Lee presents both sides. Both Brady and Hindley wrote autobiographies. Lee treats them cautiously, as well she might, but in juxtaposing, for example, their accounts of their first murder, that of trainee baker Pauline Reade in July 1963, Lee makes plain how ultimately it is impossible to reach any satisfactory conclusion about which one is telling the truth.

'True crime' addicts may find this an unsatisfactory book, precisely because it refuses to come to a neatly-packaged conclusion, but for a wider audience, One of Your Own is a measured, humane effort to get beyond the hysteria and the horror.

Peter Stanford's biography of Lord Longford, 'The Outcasts' Outcast' is published by Sutton