Joan Smith: Who cares who Jack the Ripper really was?

What is disturbing is not just the ghoulish interest, but the way the killer has been mythologised

Some years ago, I went to hear the American crime writer Patricia Cornwell speak in a London bookshop. Cornwell, who is the author of a series of best-selling novels, attracts large and respectful audiences who talk about her fictional detective, a forensic pathologist called Dr Kay Scarpetta, as though she were a real person.

On this occasion, one of them breathlessly asked whether "Dr Kay" might turn up in the UK in a future adventure. Cornwell's response was revealing, for she immediately began talking about a series of murders of young boys in the north of England - a real case, which had been making headlines that very week. Scarpetta might find herself invited to this country to help with the investigation, Cornwell said enthusiastically, blurring the line between fact and fiction even further.

I recalled this episode at the weekend, when Cornwell paid for a whole-page advertisement in this newspaper to address readers on the subject of her investigation into the identity of the Victorian killer known as Jack the Ripper. Three years ago, after spending $2m (£1.1m) of her own money, Cornwell published her book Portrait of a Killer, whose subtitle "Jack the Ripper: Case Closed", was an unambiguous statement of confidence in her success in identifying the Whitechapel murderer. Cornwell's suspect, the impressionist painter Walter Sickert, was not a new name to Ripper enthusiasts, having been fingered as long ago as the 1970s by the author Stephen Knight, who claimed Sickert was an accomplice of the "true" Ripper, the royal physician Sir William Gull.

Knight was just as confident that he had solved the case, a fact reflected in the title of his book, Jack the Ripper: The Final Solution. Not everyone was persuaded, and in 1990 the painter was unequivocally identified as the Ripper by Jean Overton Fuller in her volume, Sickert and the Ripper Crimes. Cornwell's own Ripper book caused a furore in 2002, partly because of her fame and partly because Ripper theorists are a quarrelsome bunch. Leading members of the art world were also outraged, including Sickert's biographer Matthew Sturgis, whose book, published this year, includes a postscript denying Cornwell's claim.

Visibly piqued, Cornwell is now carrying out further tests and planning a new edition of her own book. The evidence she has produced to date includes the fact that three of Sickert's letters and two of the so-called Ripper letters sent to the authorities came from "the same watermarked paper batch of only 24 sheets". This is hardly conclusive, for the vast majority of Ripper letters are acknowledged to be hoaxes; even if Sickert could be proved to have written one or more of them, it does not prove that he was the killer.

Far from convincing her critics, Cornwell's latest salvo is more likely to be seen as further evidence that she is indulging a rich woman's obsession - and blurring the line between fact and fiction once again. There are striking similarities between Cornwell's real-life quest and her protagonist's fictional pursuit of serial killers, which often exposes Scarpetta to scorn from colleagues and even suspension from a case. No one, of course, has the power to take Cornwell off the Ripper case, cold as the trail undeniably is after 117 years. But she sounds awfully like Scarpetta when she insists that "I owe it to both the victims and the man I accuse of this terrible crime" to investigate any new evidence that turns up.

Mildly entertaining as this spat among self-appointed Ripper experts may be, the fact remains that Cornwell's approach has something in common with everything else that has been written about the Whitechapel murders. In the vast literature that has grown up around the killings, no one ever asks a very basic question: why does the criminal's identity matter? Why do so many people spend so much time, energy and (in Cornwell's case) money on trying to name a man who committed horrible crimes more than a century ago? Even if someone could demonstrate beyond all reasonable doubt that the killer was Queen Victoria in drag, or an unemployed dock worker - far more likely, given what we now know about serial killers - what would it actually achieve?

Cornwell's answer, that "the Ripper's victims deserve justice and the murderer himself deserves to be held accountable", is a noble aspiration, but makes little sense, given how long they have all been dead. One thing that can be said with certainty is that a positive identification would damage the Ripper market, because the mystery of the killer's identity - like the question of who killed JFK or indeed Princess Diana, if your taste for conspiracy theories lies in that direction - is what keeps the industry going. In that sense, it is against everyone's interest to come up with a "final solution", which may be another reason why Ripper experts rubbish each other with such vehemence.

At the same time, the common factors in what we might call Ripper studies reveal something disturbing about human nature: not just the ghoulish interest people continue to take in the case, to the point of going on guided "Ripper walks" in the East End of London, but the way in which the killer has been mythologised. No matter whom they fancy for the crime, most Ripper experts come up with not just a name but a Name - Sickert, Gull, sometimes even a royal duke.

Cornwell's novels have their own share of fiendishly clever serial killers, most of whom bear as little resemblance to real life. As the convicted British murderer Dennis Nielsen once observed, if serial killers were as charismatic as Hannibal Lecter, they wouldn't need to be serial killers. In that sense, Jack the Ripper long ago ceased to be a real person and became in effect a fictional character. Most of what we "know" about him to this day is a mixture of conjecture and myth, which lends itself to a multitude of theories and does a very effective job of obscuring what the case is really about.

No matter how much they are dressed up as a Victorian mystery, the Whitechapel killings are one of the earliest known manifestations of a loathing of women so intense that it is not satisfied until it has mutilated and destroyed their bodies.

Cornwell's spat with other Ripper experts has renewed interest in a case whose enduring appeal says a great deal about the public appetite for misogyny. She is at least a woman, which is unusual in this field, and avowedly concerned about the killer's victims. But I wish she would realise that the most important thing about Jack the Ripper is not his identity. It is working out how the myth of the heroic misogynist, for which the Whitechapel killer provides the template, can finally be laid to rest.