This morning in Fairfax Circuit Court an unusual civil suit comes to trial in which the two daughters of an Annandale woman found strangled 22 months ago seek $10 million in damages from their stepfather, a prominent Northern Virginia gynecologist, for allegedly killing their mother.

Police have charged no one with the killing of Susan Davoudlarian, whose nude body was found June 12, 1983, wrapped in a blue blanket in the family station wagon at Dulles International Airport. Dr. David K. Davoudlarian has denied any connection with his wife's death.

His stepdaughters and the administrator of his wife's estate have alleged in two separate civil suits that "on or about June 3, 1983 . . . Dr. Davoudlarian intentionally and maliciously killed [Susan Davoudlarian] by strangulation."

Even if the Circuit Court jury finds that he is responsible for her death, it cannot send him to the penitentiary for her death.

The suit being tried today seeks $10 million in damages from Davoudlarian; a second suit seeks to block him from collecting on $440,000 in insurance on his wife's life and inheriting $250,000 in property. The outcome of the second suit is likely to hinge on what happens in the first trial.

Sworn depositions taken for the civil suits, including one from the doctor, have brought to light information about the family that has not previously been public, including information about the Davoudlarian marriage, Susan Davoudlarian's extramarital affairs, her apparent desire for a divorce and David Davoudlarian's temper.

County prosecutor Robert F. Horan Jr. said that there is a significant lack of evidence to prove who killed Susan Davoudlarian "beyond a reasonable doubt," as prosecutors must in a criminal court.

Civil courts, however, require only that "the preponderance of evidence" supports the accusations. Therefore, say prosecutors and attorneys, there may be enough evidence to "prove" in civil court who killed Susan Davoudlarian.

It is rare for civil actions such as this one to proceed before criminal prosecution, said Horan and others.

"I've never seen one come in in quite this manner before," Horan said.

Despite an exhaustive investigation by the Fairfax County police and the FBI, which included interviewing every cabdriver working at Dulles at the time of the killing, officials say that they have no direct evidence linking anyone with the homicide.

There is no murder weapon, no physical evidence indicating what was used to strangle Susan Davoudlarian, nothing to establish where she was killed and no witness to the killing or to the arrival of the station wagon at Dulles, they say.

"The evidence surrounding her death is totally circumstantial," said Horan.

Nonetheless, it is on that circumstantial evidence that Susan S. Rooney, 20, and Claire E. Rooney, 19, Susan Davoudlarian's daughters from a previous marriage, have tried to build a civil suit.

According to sworn testimony in depositions given by nearly three dozen people, Susan and David Davoudlarian's marriage appeared to be in trouble. According to the testimony, Susan Davoudlarian had told her friends, her daughters, her parents and others that she was extremely unhappy with her 12-year marriage and wanted a divorce.

"I had been aware for a long time that there were problems with the marriage," said a neighbor, Pamela Welham, in her deposition.

Eula Stewart, Susan's mother, said that Susan told her she was seeing a lawyer about getting a divorce. Stewart since has died of a heart attack.

And the Davoudlarians' housekeeper of 12 years, Mattie Noakes, who still works in the house on Aunt Lilly Lane where David Davoudlarian lives, testified that Susan Davoudlarian had told her that "she wanted a divorce and had asked the doctor for one . . . but he said no."

A friend of Susan Davoudlarian, Barbara Lockhart, and one of the daughters who has filed the lawsuit, Claire E. Rooney, also have said in depositions that Susan Davoudlarian was seeing other men.

Rooney said in her deposition that she knew of at least two affairs that her mother had had, one with a local man and one with an old high school flame from Tennessee.

David Davoudlarian, a native of Syria, said in his deposition that he knew nothing of his wife's extramarital affairs or desire for divorce. He said that, as far as he knew, his wife was happy. For him, the marriage was "very happy," he said.

But the depositions of several persons recount a party in fall 1980 in which Davoudlarian accused his wife of an extramarital affair with a neighbor in front of several others. Davoudlarian was not asked about that party in the parts of his desposition available to the news media. Some of those documents are sealed for privacy reasons.

David Davoudlarian told police that the last time he saw his wife on June 4, 1983, she was heading for the bathroom in the bedroom that they shared, and that he turned over and went to sleep. The next morning she was gone from the house, he said, along with the family's station wagon.

Fairfax County police believe that Susan Davoudlarian was strangled in the bedroom that she shared with her husband, then taken from the house to the airport, according to court documents.

This assumption is based on the condition of her body when found, the fact that neither the glasses nor contact lenses that she needed were with the body, and that things such as her purse and thyroid medicine, which she normally would have taken, were not with her.

After she was found, police searched the house and seized a number of items, including stained material from the bedroom carpet, the bed and the garage. Tests on the stains, according to court documents, have been inconclusive.

The night that Susan Davoudlarian disappeared there were three people other than her husband in the house: her daughters from her previous marriage, Susan and Claire Rooney, and David Davoudlarian Jr., now 9, her son from her marriage to David Davoudlarian.

All have testified that they heard nothing the night their mother disappeared.

Horan says that the discovery process of the lawsuit -- the depositions and the presentation of evidence -- has uncovered some things not previously known to police, who have been closely reading the case file.

His office will not monitor the case on a day-to-day basis, Horan said, adding, "I see no reason."

But he said that he personally will read the transcript of the case when it is completed, regardless of the outcome.