"You are my baby," Nam Tran Tran Van Chuong told her then-60-year-old son one evening in the summer of 1986, kissing his hand at the dinner table. Then, pulling out a sketch of her burial plot, she pointed to the place where her husband would lay beside her, and, on the other side, the spot where their son would join them someday.

It seemed a portrait of tranquility, after years of upheaval, for this prominent Vietnamese family. Here in Washington, the parents -- a former ambassador and his wife of royal blood -- appeared reconciled with their long-wandering son. In a Roman villa, their youngest daughter, the famous Madame Nhu, was safely exiled, and another daughter was teaching at a small North Carolina college.

One week later, on July 24, the mother and her husband, Tran Van Chuong, lay dead, crumpled one atop the other in their bedroom. And their only son, Tran Van Khiem, was arrested and accused of their murders.

The charge of patricide and matricide, a charge that Khiem vehemently denied, shocked the Vietnamese and diplomatic communities as the sordid tale was told and retold. "The end did not match the beginning," said Khiem's sister Lechi Oggeri. "For such beautiful lives, it should have been a beautiful end. The more you tell about the glories of the past, the more horrible the end becomes."

It was not the first time the bizarre or the tragic had touched this once-powerful family, whose fate seemed intertwined with the demise of a Vietnam the members once had known. Scenes from the past have been captured on front pages, recorded in books and singed into memories:1962: One daughter, her wrists slit, rushes to the palace complex in Saigon to protest the expulsion from Vietnam of her lover, an expulsion ordered by her own sister, Madame Nhu, the country's first lady. 1963: The parents, outraged by Madame Nhu's brutalization of the Buddhists, resign their diplomatic posts, announcing, "We do not wish to know her." Later that year, Madame Nhu's husband and his brother, Vietnamese President Ngo Dinh Diem, are assassinated in a coup. 1975: South Vietnam falls and the surviving family members are left to live out their lives in exile.

Now, the deaths of the ambassador and his wife and the arrest of Khiem are like the final act in a tragedy, and the denouement may be played out next month in D.C. Superior Court, where a judge will determine whether Khiem is mentally competent to stand trial for murder.

In passionate public letters and a six-hour telephone interview from St. Elizabeths Hospital, where he is being examined by psychiatrists, Khiem has talked of a global conspiracy that has come to focus on him. And he has alleged a conspiracy of a more intimate nature as well.

Khiem said his sister Oggeri and her sons-in-law have conspired to paint him as a murderer to gain control of his parents' $650,000 estate.

From her villa outside Rome, Madame Nhu has come to her brother's aid, charging in a telephone interview that her sister Lechi (pronounced Leechee) Oggeri has been "excited" by "agents provocateurs."

Lechi Oggeri's husband Etienne said of Khiem, "He is a mad dog barking. And we don't want to bark back." The Glory Days

Everyone in Hanoi, the haut monde, knew that Tuesday "was the day of Madame Chuong's salon," Lechi Oggeri recalled of the days when she was growing up. The bright and the cultured of the city would flock to their spacious, elegant home "for the pleasure of conversing," she said.

It was a particular honor to be invited to Madame Chuong's, for she was famous for her beauty -- "the most beautiful woman in Vietnam," Oggeri said. And Khiem remembers dreaming back then, "When I shall be an adult, I shall marry a woman as beautiful as my mother."

If Madame Chuong's beauty was renowned, so was her family tree. Her uncles had sat on the throne, and she was the cousin of Emperor Bao Dai, the ruler of Vietnam until he was deposed by Diem in 1955.

Chuong, whose father had been governor for years of a major province and whose brothers held important government posts, was practicing law when the three children were growing up. He was schooled in France and Algeria, the first man in Vietnam to have earned a doctor of law degree.

"We were a great family of Vietnam, very rich and very powerful," Khiem said. "In the house at Hanoi, we had . . . 20 servants."

The family of Tran Van Chuong was one of the 50 ruling families of Vietnam in those days, said Stanley Karnow, former Washington Post foreign correspondent and author of "Vietnam, a History."

Chuong and his wife were near the center of a movement to create a new Vietnam, free of French rule. Their lives and the lives of their children were always part of the roiling pot that was the politics of Vietnam, forever filled with intrigue.

In 1945, when many believed that the way to independence was through Japanese support, Chuong was vice premier in a short-lived Japanese puppet government. Later that year, when the communist Viet Minh took control of the government, Chuong was arrested. His wife, whom the Viet Minh were willing to leave behind, insisted on going with her husband.

"She was never afraid of anything," said Oggeri, proud to tell the story.

Soon the couple escaped, taking refuge in the south, and in 1947 they went to Paris. When Diem became prime minister in 1954 and then the nation's president, Chuong was named Vietnam's ambassador to the United States. His wife became Vietnam's permanent observer at the United Nations.

Their daughter was married to Diem's brother Ngo Dinh Nhu, who many believed was the power behind the president. She styled herself as the first lady to the bachelor president, but her saber-tongued comments won her another name: the "Dragon Lady."

The Rift

Half a world away in Washington, Tran Van Chuong and his wife were cutting a glittering swath in the capital's social circles. Diplomats crowded their parties; a "pedestrian traffic jam," one in 1962 was called.

But outside the ornate walls of the embassy, a family feud was about to erupt.

Chuong and his wife, cultured and dignified, were deeply concerned about growing reports that their dream of a free South Vietnam was disappearing under the oppressive hand of Diem and their daughter, who were cracking down on their opponents and restricting individual freedoms.

In 1962, seven years after arriving in Washington, Tran Van Chuong and his wife secretly began to implore President Diem and Madame Nhu to make a "sincere total change" of what they called "this bad regime."

"He spoke with his daughter several times, but to no effect," said Chuong's brother Tran Van Do, who resigned as foreign minister in 1955. " . . . He said, 'Let them stew in their own juice.' "

In August 1963, the family rift exploded on the front page of newspapers around the world.

Chuong and his wife, in protest of the Catholic Diem's brutal clashes with Buddhists, resigned. Madame Nhu, in a countercharge, claimed that her parents were fired for conspiring to overthrow the Diem regime.

Madame Nhu publicly called her father a coward.

"It had tremendous political overtones," said Malcolm Browne, then an Associated Press correspondent based in Vietnam. "It was one of those stupendous family quarrels."

Chuong began traveling the United States, lecturing as a one-man truth squad against the Diem regime. When his daughter Madame Nhu visited the United States several months later, he refused to see her in several well-publicized rebuffs.

In Saigon, the denunciations underscored gossip about family tensions that had occupied the intelligentsia for years. Radio stations were continually broadcasting the latest family rumors. Prominent stories that regularly set tongues wagging, according to Stanley Karnow, were rumors that Madame Chuong had had an affair with Ngo Dinh Nhu before her daughter married him; that another family member had asked for the use of a lawyer's wife in exchange for a loan; and that Lechi Oggeri, Madame Chuong's other daughter, was seen about town with a handsome French safari hunter.

"Rumors constantly filled the city, but discriminating between fact and fantasy was not easy," said Dennis Warner, a British correspondent who knew Khiem well.

Whatever the validity of the rumors, they were the public side of real and deeper troubles within the family. Along with the huge political chasm dividing the members, there were several intrafamily feuds, one of which centered on Khiem's sister Lechi Oggeri. And unlike most other families, this one had the political muscle to punish straying members for what was considered unacceptable behavior.

Many in Vietnam believed that legislation banning divorce, introduced by Madame Nhu, was aimed directly at Oggeri, who wanted to obtain a Vietnamese divorce and marry a Frenchman, according to Karnow. When Oggeri refused to be deterred, the Frenchman was arrested and expelled.

Oggeri slit her wrists and drove to the palace complex. She says she never intended to commit suicide; it was an attempt, she says, to impress her sister with her plight.

"My wife thought Madame Nhu might have some pity," said Etienne Oggeri, the Frenchman who married Lechi Oggeri and now lives with her in North Carolina.

Lechi Oggeri was hospitalized. What happened next is a matter of dispute among the family and is the key, Khiem says, to the current family schism.

"It shows why she hates me and Madame Nhu," Khiem said.

Etienne Oggeri says that he was wrongly arrested and expelled and that his wife was virtually imprisoned in the hospital. He says it was a conspiracy by Khiem, who wanted to control Lechi Oggeri's fortune.

Etienne Oggeri says his wife was smuggled out of the hospital by Madame Chuong, who flew in from Washington and demanded the release of her daughter. When told by hospital officials that Madame Nhu had barred Lechi Oggeri's departure, according to Etienne Oggeri, Madame Chuong flashed official papers for her daughter and announced imperiously, "I am Madame Nhu's mother."

Khiem tells quite a different story. According to him, Lechi Oggeri's behavior was scandalizing the family. "The whole of Saigon was mad at us and saying, 'Only the sister of Madame Nhu is having a lot of fun,' " Khiem said.

Khiem, who said he was trying only to help Lechi Oggeri, said he visited her at the hospital and told her that he had arranged for their mother to bring her back to Washington. He said he also told her that her lover could not return to Vietnam because he had violated the law.

One year later, on Nov. 2, 1963, while Madame Nhu was traveling in the United States, her husband Nhu and President Diem were assassinated. Nhu left the United States to live in exile in Rome. Only Khiem remained in Vietnam, a political prisoner jailed for the next three years. The Son

Khiem, the only son, played a minor role on the public stage occupied by the rest of the Tran Van Chuong family. Men in this family were leaders, and Khiem was groomed in schools in Algiers and France to carry on their legacy. But until his arrest, history had allotted him a role he never would have chosen: the part of the prodigal son.

"My brother was not satisfied," said Tran Van Do, Chuong's brother, who now lives in Paris. Chuong, he said, was upset with his son's apparent lack of success, his failure to get a regular job, his two divorces. "In a Vietnamese family, in an honorable family, we don't like that."

That early disappointment is evident in a series of letters seized by police shortly after Khiem's arrest. According to law enforcement sources who have read them, Chuong repeatedly pleaded with his heir in the early 1950s to give up his bohemian life style and concentrate on his legal studies. Khiem, then in his late twenties, had moved to Algiers from Paris to live in a beachside villa with his new German wife. His legal studies were relegated to a correspondence course with his Paris university.

"I had such a life then. Le tout Paris . . . , " he said wistfully from St. Elizabeths.

When Madame Nhu summoned her brother in 1954 to be a palace spokesman, the family hoped that Khiem would join the family ranks in more than name. It was not to be. The posting was so brief and unremarkable that many former high-ranking government officials dispute that Khiem ever held an official job at all.

"He was not in government," said Tran Kim Tuyen, the director of the country's intelligence agency until 1962, now living in Cambridge, England. "He pretended to speak for the government, but it was not true. He was the kind of person who wanted to show off."

That characterization -- the boaster, the hanger-on living off his sister's political muscle and his family's prominent name -- would follow Khiem throughout his life. After leaving the spokesman's job, Khiem worked as a lawyer and served in quasi-government positions for the next several years. He said he was appointed to the national legislature and assumed a position on the board of directors of the strategic hamlet program, a plan to isolate peasants from the communist Viet Cong.

In telephone conversations and letters, Khiem repeatedly described these roles as pivotal. "I was an important man," he said, comparing his position to that of Defense Secretary Caspar W. Weinberger.

But those who were in Vietnam at the time paint a different portrait.

"He was just a guy living off his connections," said foreign correspondent Karnow. "He is a very minor figure in the whole cast of characters."

Regardless of his political importance, Khiem lived an extremely comfortable life during his sister's reign in Saigon. Servants, a Mercedes and driver, tiger shoots, women -- all were at his disposal. Former CIA director William Colby recalls frequently "chatting" with Khiem at the local horse riding club where Khiem was president.

"I simply take my telephone if I want anything and simply gave an order," Khiem recalled. His new Vietnamese wife, whom he would leave behind, was "only one of my mistresses . . . . I had a lot of beautiful women around me."

The good life for Khiem suddenly shattered, though, in 1963 when he was imprisoned for three years after the coup. In 1968, Khiem moved to Washington to live with his parents. Khiem, then in his forties, enrolled in law classes at George Washington University and completed a translator's course at Georgetown University, but family members and friends say Chuong and his wife became disgruntled. Once again, their son was focusing his energies on women and parties; they were supporting him, and academics and finding a job took a poor second place.

"It was a matter of him not settling down," said Conrad Philos, a longtime family friend and Khiem's former lawyer. "He liked to be a bon vivant."

On April 6, 1972, The Washington Post published a letter from Khiem criticizing the sending of American troops to Vietnam. The letter devastated his father.

"It was a terrible embarrassment to {Chuong} in the diplomatic community," Philos said. "To embarrass your parents in the oriental tradition is an unforgivable sin."

Chuong ordered his son to leave, and Khiem, who missed his old life in Paris, returned willingly. "I was fed up with the U.S.," Khiem said.

There, he said, he had a child with Mireille Sautereau, a Sorbonne professor with whom he lived, and he worked part time for a French company. His parents continued to aid him, sending him $300 a month.

Sautereau said in a deposition that Khiem has not been employed since 1980. Instead, she said, Khiem was "taking care of my son . . . doing what a woman usually does at home."

In 1977, Chuong and his wife wrote new wills, replacing 1969 wills that bequeathed a house in Vietnam to Khiem. In the new wills, Lechi Oggeri got the entire $650,000 estate.

Khiem said in the interview that his parents told him during a 1977 visit to Paris that Oggeri's family had forced them to write new wills, disinheriting him. They planned to rewrite him into their wills when they returned home, he said.

The 1977 document, witnessed by a lawyer and their housekeeper, did more than disinherit Khiem. It said:

"Khiem had behaved most of his life like an exceptionally ungrateful and bad son, and has been too often to his parents a great source of worries and deep sorrow. Such behavior cannot be forgotten and forgiven in a traditional Vietnamese family."

An Unexpected End

The telephone call came on Christmas Eve 1985. Khiem, booted out by his parents in 1972, according to relatives, had been living in Paris for nearly 13 years.

Madame Chuong was calling from Washington. Would Khiem come home, she wanted to know, to care for her and his father? They were old and sick and needed him.

He reluctantly agreed and flew over in March 1986 with his 12-year-old son Pierre. They were joined later by Sautereau, the boy's mother.

The choice of Khiem to aid them seemed odd to people who knew this family fractured so long before by political and personal feuds. But according to Philos, the parents seemed to be making peace with their children. In 1977, they had visited with Madame Nhu, a meeting that would have been impossible a decade before.

What happened in the next several months in the home on Western Avenue is a matter of bitter dispute. It will be a key issue if Khiem goes to trial.

Tran Van Do, the ambassador's brother who visited in April 1986, said Khiem "lived in harmony" with his parents, rising each morning to prepare their breakfast, running errands for his mother, his demeanor "always very good . . . , joking and very pleasant."

Philos, who dined with the family and watched the tender scene in which Madame Chuong kissed her son's hand and showed him the burial plots, said her affection for Khiem was evident. Yes, there were political arguments, Philos said, but they were the polite debates of "intellectual people differing on a wide panoply of subjects." Madame Chuong, he added, also could be a tough taskmaster.

But other family members, those Khiem calls his accusers, paint a far more contentious scene, of relationships that started shakily and quickly grew worse.

"At the beginning it was all right," Etienne Oggeri, Lechi Oggeri's husband, said of Khiem's arrival at the family home. "He had respect for his mother and father. Then Khiem started to talk politics, try to impress {his father} . . . . Khiem said Diem was right. The father said the regime was rotten, a dictatorship. They were fighting, fighting, fighting."

Khiem, of course, has his own recollections of those months. They "adored me," he said of his parents. And the family never debated politics. "I am from a very aristocratic class of Vietnamese, and these things are not proper in conversation. Only rude people speak of these matters," Khiem said.

On July 23, the night before the ambassador and his wife were found dead of asphyxiation, Madame Chuong made three quick calls to her daughter Lechi Oggeri in North Carolina, according to court records.

At 9:19 p.m., she called to say there had been "a strong argument" at dinner, then abruptly hung up, saying she believed that someone was listening on the line, according to public documents filed by the prosecutors.

One minute later she called again, the documents state, telling her daughter that life in the house with Khiem "was unbearable. Your brother is very disrespectful. Very violent. And we cannot stand it." At dinner that night, Khiem "had been hitting at an imaginary person, as though he was slapping someone in the air in a threatening manner. Madame concluded, 'And I am afraid for your father.' "

The final call came at 9:56 p.m. This time she sounded "less frightened, more in control," the documents state. She explained that she had told Khiem to go back to France, that she and his father would increase his $300-a-month allowance to $500. According to the documents, Madame Chuong then told her daughter, "And now, he seems to be appeased."

Khiem disagrees with this version. The telephone calls, he said, were routine. As she often did, his mother called Lechi Oggeri to talk about her health, Khiem said.

Etienne Oggeri remembers something else about the final call between his wife and her mother. "Madame Chuong said, 'Everything is all right. Sleep in peace.' "

"My wife was happy," he said. "Then the next day at noon, Khiem called to tell us he found the parents in their room . . . . "

A Secret World

The prosecution's theory of the deaths rests on one simple notion: greed.

Shortly before he killed his parents, Khiem discovered that he had been disinherited in the 1977 wills, former prosecutor William Pease told a D.C. Superior Court hearing commissioner. Faced with no job and little money, Khiem destroyed the originals, prosecutors believe; an empty manila folder marked "wills" was allegedly found by police in the parents' home. Unknown to Khiem, though, a copy was kept in another locked file cabinet, according to Pease.

However, prosecutor Paul Howse, who replaced Pease, may never try this out theory in court. Along with the wills, police say, they found a wealth of other letters and writings that show that separate and apart from his workaday chores in the house on Western Avenue, Khiem may have created his own private world in which he is a powerful and potent figure at the center of a global conspiracy.

Since his arrest, Khiem has written letters to newspapers and an 800-page manuscript titled "The Israeli Plot Against Ngo Dinh Diem, Ngo Dinh Nhu, John Kennedy, Robert Kennedy and Me." A daily diary he kept for 15 years has been seized by investigators.

The documents prompted prosecutors to seek mental examinations for Khiem after he rejected an insanity defense, and psychiatrists at St. Elizabeths last month told Chief Judge Fred Ugast that Khiem was not competent to stand trial, a finding that could weigh heavily with the judge when he decides this issue. Khiem's lawyers, Michele Roberts and Mark Rochon, have disputed the competency finding and told the judge last week that Khiem wants to stand trial.

It is not clear when Khiem's ideas about a conspiracy began to develop, but in one 1983 letter from Paris, written on the anniversary of President Kennedy's assassination, Khiem accused the Soviets and Israelis of killing Kennedy "to prevent {Kennedy} from getting me out of jail."

On the morning his parents were found dead, according to documents filed in court, he warned of an assassination plot in a letter to President Reagan.

"You are lucky because I know who will kill you and why they will kill you . . . . The only way to stop them is hence a book, and the only person capable to write this book is I."

Khiem stridently denies that he is insane and has claimed repeatedly in court and in interviews that his hospitalization is further proof that conspirators want to silence him. He places his sister Oggeri's two sons-in-law at the center of the conspiracy.

Madame Nhu agrees with her brother's contention that someone is trying to quiet him. She, however, says she believes that her parents died of natural causes.

"They {members of the legal system} have decided to finish with him," she said. "He knows things about the U.S." Nhu, who, her sister says, tried to persuade her to change her story, now wishes that everyone would leave the family alone.

"This is a family affair," she said, ending the interview.

On July 30, 1986, Tran Van Chuong and his wife were buried side by side on a hillside at the Rock Creek Cemetery in Northwest Washington. Their headstones read: Ambassador Tran Van Chuong and Princess Nam Tran Tran Van Chuong.