LIKE all the best romances, it began with a smouldering glance and “electricity in the air”. It ended with a bungled kidnapping, attempted murder and salacious accounts of lesbian hanky panky.

More than a decade after Patricia Cornwell, the bestselling crime novelist, was unwittingly thrust into an explosive tabloid saga involving revenge, obsession and scantily clad FBI agents, one of the leading characters has decided to tell her story.

In Twisted Triangle, a book to be published in April, Cornwell’s brief lesbian dalliance with an FBI instructor named Margo Bennett is subjected to excruciating scrutiny - not to mention excruciating prose of the “As their eyes met . . .” variety.

Bennett’s decision to tell her story to a professional ghost-writer has reopened a painful but mostly farcical episode of seduction, betrayal and bullet-proof vests. Cornwell long ago shrugged off her affair with Bennett as “not even two trips over the rug . . . it was very brief in every way you can imagine”, she told Vanity Fair in 1997.

Yet the romance is resuscitated in gruelling detail in Prolonged Embraces, the central chapter of a 304-page account of Bennett’s ill-fated marriage and her husband’s eventual implosion. Gene Bennett is serving 23 years for a variety of spectacularly inept offences.

The book casts intriguing light on Cornwell’s complicated sexuality, but mostly it highlights the perils of celebrity romance. Sooner or later, however much time passes, discretion gives way to economic reality, and confidences will be betrayed.

In the summer of 1991 Cornwell - known to friends as Patsy - turned up at the FBI’s training centre at Quantico, Virginia. Cornwell was a successful novelist, widely praised for minutely researched crime fiction featuring her heroine Dr Kay Scarpetta, a forensic pathologist.

At the time both Bennett and her husband were FBI agents, although their marriage was under strain. Margo had discovered that Gene was running a variety of illegal schemes; he had turned to pornography and kept pressing his wife to “do a threesome”.

Cornwell became a regular visitor to Quantico where she sat in on courses for her research. On one occasion in early 1992 she found herself alone with Bennett. “This was not ordinary girl talk,” writes Caitlin Rother, the book’s author. “As they sat in chairs next to each other, Patsy kept swivelling around and touching Margo’s leg with the toe of her shoe . . . it felt dangerous. Wrong. Thrilling.”

One toe led to another, and soon the two women were sharing what Margo described as “the most tender kiss I had ever had . . . I was mush”.

In subsequent encounters, Cornwell talked about “growing up with her mother, who had suffered from mental illness . . . [and] how she’d been molested as a child by a security guard”.

The intimacy duly led to bed - “a soft, inviting sea of powder blue”. Margo felt “calm, complete, satisfied”. Patsy said: “That was wonderful.”

Yet no sooner had the romance started than both parties started backing away. Gene Bennett made himself unpleasant to Cornwell, who told Margo: “He scares me. I don’t trust him.” The pair eventually agreed to “just be friends”, writes Rother.

That is where the affair should almost certainly have ended, with both parties having a professional interest in keeping their private lives private. Yet as the Bennett marriage collapsed Gene became violent and threatened to challenge his wife for custody of their two children.

Margo Bennett retaliated by telling FBI investigators details of one of her husband’s money-spinning scams. Gene in turn responded by filing divorce papers claiming that the marriage had broken up because of his wife’s affair with “another woman”.

It was only a matter of time before the media got hold of the story but it was not until much later, after Gene had served a brief prison sentence for fraud and Margo had resigned from the FBI, that Cornwell’s name emerged in the couple’s divorce proceedings.

According to documents cited by the book, Gene claimed his wife had become “totally infatuated” with Cornwell. Bennett said he had secretly followed Margo to her “rendezvous” with Patsy and observed them “hugging and kissing”. He claimed to have found “lingerie, sex toys, lesbian pornographic material, etc” in her car.

In 1997 the divorce finally exploded into violence. As most newspapers pointed out afterwards, Cornwell herself would not have dared write a chapter so improbable: Bennett took his wife’s church minister hostage and attempted to lure her to the church to kill her.

Margo turned up with bullet-proof vest and revolver. When she saw the masked kidnapper and heard his voice she realised it was her husband, dived behind a desk and opened fire as if she had been Jodie Foster playing Agent Clarice Starling in The Silence of the Lambs. Unlike Foster, she missed her target but hit a door frame.

It was back to jail for her husband and out of the closet for Cornwell, who was subjected to a barrage of tabloid exposés, most of them featuring the words lust, seduction, blame, betrayal and boudoir.

Rother and Bennett asked Cornwell to cooperate with the book but she declined all interview requests. Her office had no comment last week.

Her last words on the affair now to be known as the Twisted Triangle may have been uttered as long ago as 1997. “I was very stupid,” she said.

Crime pays

* Cornwell is the world’s bestselling female writer after JK Rowling
* Her novels have earned her over £71m and are translated into 32 languages
* Kay Scarpetta is the name of a protagonist in Cornwell's novels
* Her most recent novel, Book of the Dead, was top of The Sunday Times bestseller list for eight weeks
* Her first crime novel, Postmortem, was rejected seven times before being published in 1990
* Her nonfiction book, Portrait of a Killer, alleges artist Walter Sickert was Jack the Ripper
* She rarely leaves the house without a bodyguard because of her fear of a stalker

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