Patricia Cornwell: The paranoid detective

She's been anorexic, bulimic, drunk at the wheel and out of control. She's difficult, obsessive, driven. Her head is full of fear, her books full of the serial killers and gruesome autopsies that have earned her a £100m fortune. Now the novelist has turned detective, and she's hot on the trail of Jack the Ripper

In the century since his infamous Whitechapel murders, the search for the identity of Jack the Ripper has consumed numerous authors and armchair detectives, most as obscure as the Ripper himself. But the latest investigator into Britain's most famous unsolved murder mystery is in a different league. In 10 days' time BBC's Omnibus will devote an hour to following Patricia Cornwell, America's reigning queen of crime fiction, as she mounts her own hi-tech assault on the Ripper case, using methods familiar to fans of Dr Kay Scarpetta, the forensic pathologist who is Cornwell's heroine and alter ego.

The parallels don't end there. If Cornwell sees herself as Scarpetta, the Ripper is the real-life ancestor of the pitiless serial sex killers Scarpetta tracks down – and is in turn tracked and threatened by – in the 11 novels of the series that has made Cornwell a fortune estimated at £100m.

Last year she announced she was "100 per cent certain" that the Ripper was the Victorian painter Walter Sickert, after she spent £2m buying up 32 Sickert paintings and the painter's desk to test for DNA, cutting up one canvas and flying her own team of forensic scientists to London. When science failed (no DNA was recovered), Cornwell fell back on art criticism, claiming Sickert's paintings following the murder of a Camden Town prostitute reveal his guilt. Art historians rushed to scoff at her conclusions, pointing out that Sickert shared a taste for painting low life with other artists of the time, and painted from photographs.

Patricia Cornwell vs Jack the Ripper may not be quite the true crime Battle of the Giants the BBC had hoped for, but it's certainly proving controversial – which is typical of Cornwell. Petite in person (5ft 3ins but she looks smaller) and smartly dressed, she is a giant in terms of fame and sales figures. Though she's won most of the top mystery awards (in 1990, her first Scarpetta novel, Postmortem, won five major US and European awards – a unique achievement), her real peers are not her fellow crime writers but a select group of blockbuster authors such as John Grisham, Tom Clancy, Stephen King and J K Rowling. Sadly, wealth and celebrity haven't bought Cornwell happiness or even peace of mind. Described as "difficult", "paranoid", "driven" and "obsessive", she lives in high-security houses, travels with a phalanx of assistants and bodyguards, and owns a small arsenal of guns. In her life as well as in her novels, Cornwell seems convinced there are Rippers everywhere.

Patricia Daniels (her maiden name) was born in 1956 in Miami, Florida. Her parents divorced a few years later and her mother moved Patricia and her two brothers to Montreat, North Carolina. Mrs Daniels, who suffered from depression and had to be hospitalised from time to time, sought help from the Rev Billy Graham, the godfather of American Christian fundamentalism and self-appointed spiritual confidant to successive US presidents. The Grahams lived two miles up the road from the Daniels family. Ruth Bell Graham, Billy Graham's wife, acted like a second mother to the young Patricia, encouraging her to write. The father who deserted her, the mentally unstable mother, an unhappy spell with a foster family, and a reported sexual assault combined to create an abiding terror in Cornwell. "My biggest battle has always been about fear," she has said.

After graduating from Davidson, a private liberal arts college in North Carolina, where she now endows a scholarship for creative writing, she married one of her professors, Charles Cornwell. By the time they divorced 10 years later, Patricia had progressed from a summer job compiling TV listings for The Charlotte Observer to crime reporter to a job at the medical examiner's office in Virginia. It was all research for the crime novelist she planned to be, though her first published book in 1983 was A Time for Remembering, a biography of Ruth Bell Graham. After three thrillers were rejected by publishers, Cornwell took an editor's advice and turned a then minor character, Kay Scarpetta, chief medical examiner for Virginia, into her main protagonist – and the rest was a best-selling mystery.

Cornwell had found her formula: roughly, Hannibal Lecter meets Silent Witness – monstrous serial killers whose Grand Guignol violence is offset and eventual-ly contained by detailed descriptions of autopsy techniques, forensic science and computer technology.

But behind the formula lies the fear. In the opinion of British journalist and fellow thriller writer Sarah Dunant, "For her first five or six books, she's a cracking writer, a great writer of adrenalin. She winds you up and scares the shit out of you. However many locks and bolts I have on my door, she persuades me of the ability of violence and evil to break through at any moment."

According to another crime novelist, "In [Cornwell's] view, bad people fill the world, and not just bad people – twisted, ultra-violent, evil psychos. It's a paranoid view of an America where there are a few decent people and marauding groups of evildoers."

Though not a believer, Cornwell's world-view closely follows US Christian fundamentalism with its Manichean split between good and evil. She endorses the death penalty, dismisses social explanations for crime and seems to believe that serial killers – an extremely rare phenomenon – are the norm. While clearly the product of her traumatic childhood rather than a developed political philosophy, Cornwell's views fitted the mood of Reagan's America when she had her first success. She was also part of the "new wave" of feminist crime writers alongside Sara Paretsky, and Sue Grafton. In Cornwell's work, though, women are both the ultimate victims and the ultimate action heroines or – uniquely with Kay Scarpetta – both at the same time.

Cornwell seems to see her own life in much the same terms. Even more than most authors, she identifies with her character, wearing a wedding ring bought in Verona, Italy (Scarpetta's supposed birthplace) and giving Scarpetta her tastes for Colt revolvers, Mercedes cars and helicopter rides – Cornwell is a qualified pilot and owns a Bell 'copter – along with a passion for cooking Italian dishes. The richer and more secure Cornwell has become, the more she feels under threat by "crazies" in general.

Yet most of the traumas in her very public life have come out of herself. She's been anorexic and bulimic, crashed a car while drunk and had treatment for alcoholism, been misdiagnosed as manic depressive and was caught up in a bizarre crime in the mid-1990s when she had a lesbian affair with Margo Bennett, an FBI agent. Bennett's deranged husband, Eugene, kidnapped a church minister and shot it out with Margo. He went to prison for attempted murder.

Characteristically, Cornwell refused to become a pin-up for lesbianism and claims she is "attracted to both sexes", though friends say her sexuality is in no real doubt (the novels have a politically correct lesbian character in Scarpetta's niece Lucy). Capable of great generosity, there's a streak of self-pity in her public utterances and a clear preference, again shared with Scarpetta, for the dead over the living. Dead bodies, she says, speak to her, but the research she does for her books is a kind of sacrifice she undertakes on behalf of the rest of us, on whose behalf she stares evil in the face and pays the psychic price. For Cornwell, it seems, her life will always imitate her art.