The Line Between Madness and Culpability : RANCHO MIRAGE: An American Tragedy of Manners, Madness and Murder, <i> By Aram Saroyan (Barricade Books: $18.99; 366 pp.)</i>

When sheriff’s deputies arrived at the Rancho Mirage home of Bob and Andrea Sand in the early morning of May 14, 1981, they found Bob dead in a pool of blood. He had been stabbed more than 20 times.

Andrea said she had been asleep in the guest bedroom when she heard noises from the master bedroom and went in to check on her husband. She said she saw figures running out of the bedroom and into the night.

Investigators weren’t comfortable with her story.

The rest of Aram Saroyan’s “Rancho Mirage” is a whodunit. More importantly, it is a search for the real Andrea Sand: Is she the victim of a life of brutalization by men? A pretty and intelligent, if uneducated, woman who was pushed to the limits of her endurance by a sick husband? Or, is she legally mad, unable to understand the consequences of her actions--incapable of distinguishing reality from fantasy?

Saroyan’s 13th book is a true story about the blurred lines between fantasy and reality, psychopathology and deceit, self-preservation and murder. But it also probes the conundrum of insanity as a legal defense, and the questionable ability of expert witnesses to illuminate the truth.

After more than a year-long investigation, police finally arrest Andrea for the murder of her husband. During the court proceedings, which make up much of the book, no fewer than 10 psychiatrists and psychologists are summoned. And even though those testifying for the prosecution at least in part concur with the defense that Andrea is borderline psychotic, the court finally finds her guilty. Is she?

When Andrea, 38, first meets Bob Sand, at 68, a wealthy wheelchair-bound retiree, she is revealed to be a woman whose strategy for survival is to please men. From an abusive childhood, to a forced marriage at 16 to a man who had raped and impregnated her, to breast enlargement at a man’s suggestion to get a topless dancing job, and finally to prostitution, Andrea has lived by accommodating men--sometimes for just a night, sometimes longer.

Andrea and Bob didn’t meet at Parents Without Partners. They were introduced by a madam, who told Andrea Bob Sand was tiring of paying for different women and wanted a full-time partner. She warned Andrea that he was sometimes rough, but generally treated the women well.

It’s no stretch to surmise that in marrying her, Bob figured he was buying himself a full-time whore. But Andrea saw it as a step closer to elusive respectability.

Soon after getting married, the couple moved from his Wilshire Boulevard condominium to The Springs, an exclusive enclave in the cluster of golf course communities in the desert southeast of Los Angeles: the retreat of former movie stars and Presidents and, most recently, Tammy Faye Baker.

But if the community is emblematic of all that the supposed Good Life has to offer, a carefree Valhalla in the sun, then the Rancho Mirage of this story is the flip side of that dream.

This book is a stretch for Saroyan. Early in his career he won a National Endowment for the Arts award for poetry, and went on to write three intimate books about the lives of his parents, writer William Saroyan and Carol Matthau, now the wife of actor Walter Matthau. Later volumes included “Genesis Angels,” the life of beat poet Lew Welch, told in a narrative that effectively replicates the jazz/hipster cadences of the beats.

This time, however, Saroyan reaches farther outside himself in telling what he calls “an American tragedy.” But the reader will have to decide whether, in fact, Andrea’s story is tragic at all.

Bob Sand, it turns out, gets his sexual kicks by involving Andrea in fantasies that are recalled in a level of detail many readers may find offensive. The fantasies, Andrea later claims, were either narrated to her by her husband in lurid detail, or he actually caused them to be acted out--hiring participants to enter the couple’s bedroom. It is from here that the mystery of the book is launched.

One question the story seeks to unravel is what really happened behind the closed doors of the Sands’ house and what only happened in Andrea’s mind.

It was nearly 30 years ago that Truman Capote’s “In Cold Blood” laid the groundwork for the true crime novel. He created a new genre by weaving the presumed inner workings of the criminal mind around the fabric of real events. But he also wrote about a new kind of American experience: the disintegration of normal constraints and the emergence of madness and violence from deep in the American soul.

Beyond that, he brought into question the ability of the law to draw the line between madness and culpability.

Unfortunately, he also helped to spawn a school of “as if” writers such as Joe McGinnis, Albert Goldman and Kitty Kelley, who, when they couldn’t penetrate the inner thoughts of people, or ascertain what they did out of the public eye, simply filled in the gaps with speculation: “as if” they had thought this, as if they had done that.

To his credit, Saroyan shuns this seamy side of what used to be called “new journalism.” This is the book’s strength and also its weakness. Without blurring fact with fiction, he lays out the details he has gleaned from meticulous research of the public and medical records and interviews. And the research is impressive. Unfortunately, in the book, as in life, there are gaps in knowledge, that lead to gaps in dramatic action.

On one level, “Rancho Mirage” is a skillful chronicle of events leading to the collision of disparate lives. But we finally can’t be sure if it’s the stuff of tragedy.

If, in the end, we believe with Saroyan that this is an American tragedy of the kind playwright Arthur Miller said results from the “consequence of a man’s total compulsion to evaluate himself justly,” with his subsequent destruction in the attempt, then we may be moved to pity for Andrea Sand, who, after the jury pronounced her guilty of murdering her husband, shouted out, “I killed him because he called me a whore!”

On the other hand, we may concur with the jury that Andrea Sand was merely a pathetic woman who killed the last in the long string of men who had failed to give her the respect she craved.