Natasha Cooper is the author of more than ten crime novels. She examines the issue of crime from a different perspective

Once again the weekend papers are full of crime. The figures for recorded offences for July are said to show the biggest rise for years. Street crime is becoming more common and more violent. Drug addicts are shoplifting and robbing to feed habits that cost thousands of pounds a month. Fear of crime is everywhere. And yet in the list of best-selling hardback fiction seven of the top ten are crime novels or thrillers. We hate and fear crime, and yet we want to read about it in both fact and fiction. Why?

Most people are afraid of crime, and anyone who has ever been a victim dreads a recurrence. There was a time when I lived in a roughish area of South London and was burgled so often that I could hardly bear to leave the house. There was never much to take - the toaster, the television, the few bits of jewellery I had left after the last break-in - but the value of what went was nothing compared with the loss of my sense of safety at home. I dreaded coming back to find the front door swinging on its hinges again, or another window broken. The fear was worse, of course, when the thieves broke in at night while I was there. That happened three times.

I was lucky. There were other people in the house each time and the intruders were scared off. But it was never hard to imagine a different outcome, even without news reports and accounts from friends who, not so lucky, suffered serious violence. Years later, I poured the remembered fear into my novel Fault Lines, in which a social worker is woken by a scuffling sound in the night and goes downstairs to investigate what she thinks must be an invasion of mice, only to discover a violent intruder.

Adult fairy tales
Writing that book provided a kind of therapy, and I find that reading other people's novels can have a similar effect. In many ways, crime fiction gives adults what children take from fairy tales: the reassurance that comes from seeing your worst fears acted out in the suffering of imaginary victims, whose tormentors are ultimately punished.

Fairy tales may end with those wonderfully familiar words, 'and they all lived happily ever after', but these days a large number of adult crime novels have open endings, in which it is very clear that some criminals will escape and few victims or investigators can expect unalloyed happiness. While that takes something away from the reassurance, it makes what is left more convincing because the stories themselves are more realistic. Anyone who reads the papers knows that less than a quarter of all crime is ever solved, although the clear-up rate for violent offences is much better at two-thirds.

Some realism is essential in crime fiction, but too much destroys the pleasure that all readers have a right to expect. They have to believe in the imaginary world writers create and enjoy it, as excitement drives them on towards the denouement. Too much research, too much detail, too much reality can destroy all that.

Copycat criminals
There are other, more serious, hazards. I have often been asked in interviews and at literary festivals whether I worry about adding to people's fear of crime or giving ideas to criminals. The second question is easy to answer. I cannot imagine anyone capable of serious violence wanting one of my novels to tell him how to hurt someone else. For one thing, I am not particularly interested in exactly how my villains do what they do; I'd far rather write about why they do it and how they are caught. For another, there are accounts of real crimes published every day in every newspaper and reported every evening on television. No copycat needs to turn to fiction for ideas.

In the past there has been the occasional report of a killer citing a novel as his inspiration, but it is very rare. I seem to remember that Agatha Christie included a death by poisoning with thallium in one of her books and a later murderer said he had got the information he needed from it. Even if that's true, it can only have been the type of poison the killer took from the novel.

Fiction cannot make anyone violent. Frustration, whether sexual, financial, social, professional or emotional, usually provides the impulse to kill, and there are all kinds of reasons why some people are unable to resist it. Alcohol and drugs are involved in a lot of violent crime; brain damage may sometimes have a part to play, as may abuse in childhood, poor parenting (or even no parenting), a variety of other physical and emotional stresses, or even, if the latest research is to be believed, a diet lacking vitamins and essential fatty acids.

The other question is harder to answer. I think it is possible that crime novelists have added to the general fear of crime, although again real crime reported on screen and in print seems more likely to cause trouble.

Fear of the known
Whatever the cause, fear of crime has serious consequences for the way we all live. Like most women, I am reluctant to walk alone at night, and yet it is young men between the ages of 16 and 24 who are at far greater risk of violence than women of any age. Almost no children are allowed to roam around on their own as they did in the 1950s, and yet they are at more risk from family, carers and acquaintances than they are from strangers.

And that sums up the sad truth about violent crime. A great deal of it is committed by people known to the victim. Yes, there are some people who are killed by strangers. A few have been caught in the crossfire of drive-by shootings. The rise in gun crime in big cities like London and Manchester is deeply worrying. Even so, statistically you are still more at risk of violence from your family and friends than you are from strangers. Police figures don't differentiate between violent crimes committed by strangers and by people known to the victim, but a report of the 2000 British Crime Survey confirms that the average risk of violence from a stranger in 1999 was lower than that from an acquaintance.

Perhaps that gives the key to the greatest mystery of all: why are we so excited by crime in fiction? Could we be projecting the violent impulses we sense in ourselves and those around us on to the idea of an 'evil' stranger? I don't know, but if we are, that seems a thoroughly useful strategy for dealing with furies we cannot bear to acknowledge and would never let out. Just as we can safely experience our own fear through the emotions of the victim of a fairy tale or crime novel, so we can project our unacceptable impulses on to the villain and watch in real satisfaction as he is caught and punished. With fiction, we can have it both ways.