Larry Wu-Tai Chin, the former CIA translator convicted two weeks ago of spying for the Chinese for more than 30 years, apparently committed suicide early yesterday in his jail cell by tying a plastic bag over his head, federal authorities said.

The 63-year-old Chin, who told reporters after his conviction that he had "nothing to regret," was found in his bed at the Prince William-Manassas Regional Adult Detention Center at 8:45 a.m. by jail personnel, according to a statement from the U.S. Marshals Service.

Completely covered by his blanket except for his feet, Chin was found with a plastic bag tied over his head with a shoelace, according to sources familiar with the case. He was not breathing, the sources said, and despite emergency unit rescue attempts he could not be revived. He was pronounced dead at 9:35 a.m., the Marshals Service statement said.

"Although Mr. Chin's death appears to have been the result of his own intentional actions," the statement said, "no categorical statement regarding the cause of death is possible or appropriate until the autopsy report is completed by the medical examiner."

Prince William County Commonwealth's Attorney Paul B. Ebert said he was conducting an investigation but would not issue a formal report until he sees the results of an autopsy to be performed today at Fairfax Hospital by the Northern Virginia state medical examiner's office.

A letter to Chin's wife Cathy was found in his cell, according to informed sources. Sealed in an envelope, it is written in Chinese, and federal authorities plan to have it translated this weekend.

Chin, who was alone in his cell yesterday, had breakfast there at 6:30 a.m., according to the Marshals Service statement. It has not been disclosed how he obtained a plastic bag and shoelace.

Last week, Chin told a fellow inmate that if he was given a life sentence, he would not serve it, according to knowledgeable sources. Instead, the sources said, Chin, a diabetic, said he would induce a coma by eating sugar.

This suicide threat was reported to prison authorities, who placed Chin under close scrutiny for a time, a source said. Jail authorities had a doctor and nurse examine Chin, and they reported that he was not suicidal, the source continued, and Chin was taken off the "suicide watch."

Officials at the jail would not comment on this account. They said that on a suicide watch, a prisoner is placed in a solitary cell and checked at least every 30 minutes.

Chin, like other federal prisoners awaiting trial or sentencing in Northern Virginia, was being held in a local facility. At his sentencing, which was scheduled for March 17, Chin faced a maximum of two life sentences plus 83 years in prison and $3.3 million in fines. After sentencing for his Feb. 7 conviction on espionage, conspiracy and tax evasion charges, he would have been transferred to a federal prison.

Chin seemed upbeat and relaxed during a half-hour conversation at the jail with two reporters three days after his conviction.

In that conversation he said he had passed classified information to the Chinese from his CIA job as part of a personal "mission" to reconcile China and the United States. Chin had testified that he passed only information that put the United States and its intentions toward China in a good light, and he denied passing military secrets. A life sentence, he said in the interview, "was a very small price to pay" for fostering that friendship.

Chin's wife identified his body at the Prince William Hospital, where it was taken from the jail. The Chins have two sons and a daughter.

Chin led a multifaceted life that saw the tall, slender man go from a student of English and journalism at Peking's Yenching University in the late 1940s to a long CIA career to a spying conviction.

Patriarch of a family numbering about 40, Chin was a man who loved to gamble, taking numerous jaunts to Las Vegas to play blackjack, and to invest in real estate. A review of land records disclosed that he owned property valued at more than $700,000, including 16 condominiums and seven houses, in the Washington area, Baltimore and Las Vegas.

An avid traveler, he lived modestly in a one-bedroom apartment in Alexandria. Though Chin was fastidious in keeping records and personal diaries of his activities, sources familiar with his journals said yesterday that the papers shed little light on his emotions or feelings. One described them as "very sterile."

At the CIA, where Chin worked in the Rosslyn office of the Foreign Information Broadcasting Service until his retirement in 1981, he was known as a reliable, top-notch translator and analyst. Chin, who served as a CIA consultant until his arrest, was "one of the best," a supervisor, Cy Braegelmann, testified at his trial.

But at the same time, Chin, who according to prosecutors passed information to the Chinese on Chinese POWs during the Korean War, met regularly with Chinese intelligence agents from 1970 on. Testimony showed that he furnished them with classified documents, receiving at least $180,000, which he stashed in Hong Kong banks.

Chin, a naturalized American since 1965, was a reserved man. During his trial in U.S. District Court in Alexandria, he maintained a calm, quiet demeanor. While being taken from the courtroom just after his conviction, Chin paused at the door, turned to look at his wife and sons in the gallery and stood for a long moment staring sadly at them.

Justice Department spokesman John Russell said yesterday that the department had not determined whether Chin's family or estate would be liable for the criminal fines that would have resulted from his sentencing. Russell said "we would have to do some legal research" as well as make an accounting of Chin's assets and of whether the family should be held responsible for his wrongdoing.

U.S. District Judge Robert R. Merhige Jr., who presided at the trial, said yesterday, "I'm distressed when a thing like this happens to anyone . . . . The family has my sympathies."

Chin, a Quaker, said this week in an interview for the CBS "Nightwatch" program that members of his faith "are noted for their courage to do things according to the dictates of their conscience without consideration of the consequences."

"Even if I can foresee the entire . . . scenario, I think I will do it," Chin responded when asked if he would do the spying over again.

Asked how he would respond to an offer of political asylum from China, Chin said, "If I can go to China, I would go to China." Only a week before, asked the same question by reporters, Chin replied that he would "have to think about it. This is my country. I want to stay here."

"I am a patriot," he said in the television interview, "of the United States and the People's Republic of China." Staff writers John F. Harris and Saundra Saperstein contributed to this report.