The son of a former South Vietnamese ambassador here was charged last night with murder in the deaths of his parents, whose bodies were found Thursday in a bedroom of their upper Northwest Washington home.

D.C. police said yesterday an autopsy had revealed that the victims, Tran Van Chuong, 88, and his wife, Nam-Tran Chuong, 75, died of suffocation and that they apparently had been beaten.

Charged in the slayings was 60-year-old Tran Van Khiem, who, along with his wife and 12-year-old son, had been living with his parents at their home at 5601 Western Ave., where he was arrested on a warrant about 7:45 p.m.

Police sources and family members said that Khiem, a lawyer and a former paramilitary leader in South Vietnam, may have had longstanding differences with his parents over political philosophy, but that no motive for the slayings was immediately apparent.

Only hours before his arrest, Khiem told The Washington Post in a lengthy interview that he had left his legal practice in Paris early this year to take care of his aging parents here and had "no reason" to kill them.

"The police have a theory. They said, 'You hit him the father with your karate fist,' " Khiem said. "I said, 'Your theory of me killing my parents does not hold water. What would be the reason?' "

The pajama-clad bodies were found about 10:30 a.m. lying on the floor in their second-floor bedroom, the wife's body sprawled across her husband's.

According to police, the father's nose had been broken and his wife had "apparently been hit by some kind of a blow" that "smashed in" her chest, breaking at least one bone and crushing a main artery to her heart.

Sources said both had been either "smothered by pushing their faces into the rug" or by rags held over their faces, and that they had been dead eight to 10 hours.

Tran Van Chuong and his wife gained widespread attention in 1963 when he resigned as ambassador to the United States and she stepped down as South Vietnam's permanent observer at the United Nations to protest what they described as the brutal suppression of Buddhists under the regime of South Vietnam President Ngo Dinh Diem.

The couple's public break with the Diem regime also exposed a family rift: Mme. Ngo Dinh Nhu -- their daughter and Khiem's sister -- was Diem's sister-in-law.

Her husband was widely regarded as the power behind the throne, and Madame Nhu's rumored ruthlessness in affairs of state earned her a nickname as the "Dragon Lady."

Khiem, who held a high post in the Diem government's program of fortifying South Vietnamese hamlets in the early 1960s and briefly served in that country's national assembly before the Diem government fell, strongly opposed the use of U.S. forces in the war there.

D.C. police sources said Khiem and his parents had been estranged for years because of their philosophical differences.

According to these sources, Nam-Tran Chuong had called a relative recently to complain of "a lot of arguments" with Khiem and that he had become "very brutal toward them."

In the interview yesterday, however, Khiem said life with his parents had been "very quiet" since he joined them here, and that they enjoyed "a very American kind of life" together.

"We had a normal life, a simple life," said Khiem, sitting in the living room his parents had decorated with antique oriental furnishings and photographs from their days as diplomats.

"In any crime, you must have a valid reason," he said.

Khiem said the bodies were discovered by a housekeeper who went to the bedroom where his parents were thought to be resting, to tell them he was leaving the house.

Khiem said he followed the housekeeper into the room and "I approached and I saw" the couple dead. But he said he "was not astonished" because both "were very old" and had expected to die soon.

The reason Khiem had come to Washington, he said, was in response to a telephone call last December from his mother, who asked for his help because "the end was near" for both parents and they needed to be looked after, Khiem said.

"She said, 'You have to come right away. Your father is trembling,' " Khiem recalled. "Vietnamese hate to go to the nursing home. They prefer to stay here, if they can have a man in the house."

Khiem said his parents spent most of their time reading newspapers and books, corresponding with friends and tending their flower garden. They rarely had visitors or left the house, he said, ordering all their provisions delivered from a local grocery store, "everything from toothpaste to ham."

He said his father in the last year had had problems walking and had fallen several times, breaking several teeth. Khiem said he believed his father had fallen and died on his way to the bathroom, and that his mother must have tried to lift him "and had a stroke."

"It annoys me. I knew that they will die," Khiem said. "It was all prepared, so I was not astonished. But I was not prepared to see them both die at the same time."

Other friends and relatives gave conflicting reports on the recent state of the couple's health. Bui Diem, who came here as Vietnamese ambassador in 1967, said he had seen them a few months ago and found them well. "They are getting old, but somehow in good shape. They had been in ill health for some time, but he recuperated and she recuperated in spite of old age."

But Tran Van Chuong's brother, Tran Van Do, who lives in Paris, said he visited the couple in April here and they seemed "in bad health." Both, Do said, had "difficulty walking."

Yesterday, a grey metal cane hung from the polished bannister at the foot of the stairs leading to the couple's bedroom.

The couple led a glittering life in Washington's diplomatic community after arriving in this country in the 1950s.

One black-and-white photograph hanging in their living room shows them seated at a White House dinner with President and Mrs. Eisenhower.

Former State Department official Paul Kattenburg, now a professor at the University of South Carolina, remembers the couple as "a very charming" pair who entertained elegantly at the South Vietnamese Embassy on R Street NW.

"She was absolutely gorgeous . . . like her daughter Madame Nhu ," Kattenburg said. He described Tran as a "very tiny man, very engaging, very sincere, honest, with a good deal of integrity."

Their glamorous life as representatives of South Vietnam ended, however, with their resignations in 1963. Tran Van Chuong returned for a time to South Vietnam to become what some observers called a "one-man truth squad," following his daughter around the country and contradicting her pronouncements. The couple eventually settled into a comfortable exile in Washington with no particular financial concerns, according to newspaper accounts at the time.

Khiem, meanwhile, served a brief term in what many viewed as a puppet legislature under Diem. Educated in the law in France, Khiem said he had become involved in the military struggle as a leader of Diem's plan to keep strategic hamlets in the Vietnamese countryside out of communist hands.

Some observers claimed the effort brutalized the peasants and drove many to the Viet Cong.

When the Diem government fell, Khiem said, he spent three years in prison, then moved to Paris.

He said he returned to Washington in the late 1960s to live with his parents and studied law for several months at George Washington University, while continuing to advocate the reunification of the two Vietnams under a neutral government.

Khiem said he left for Paris again in 1972, and had worked most recently as a contracts lawyer for Framatome, a company he described as involved in nuclear reactor construction.

His wife Mirielle described herself as an assistant director in the communications school at the Sorbonne.

Mirielle Van Khiem, 42, seemed fatigued yesterday while Khiem spoke quickly and energetically, sitting in an overstuffed chair.

On Thursday, they said, investigators had questioned them extensively at police headquarters and both were annoyed that police had also questioned their 12-year-old son Pierre.

"They say that I'm very smart, so they start calling me professor," said Khiem in heavily accented English, sometimes breaking into French with his wife. "One of the police officers called my wife 'Honey,' " he said, frowning. "My wife is fed up with the United States."

Khiem laughed when he said homicide detectives had accused him of hitting his parents with his fists, then looked for bruises on his hands.

He stretched his hands out to show his knuckles, explaining they were dark because "I am a yellow man" and because he performs push-ups.

"I said, 'Gentlemen, your theory is ridiculous.' " Staff writer Saundra Saperstein contributed to this report.