Nearly two months after a state court overturned the murder conviction of David Wong, an illegal Chinese immigrant accused of stabbing a fellow inmate in an upstate prison in 1986, prosecutors in Plattsburgh, N.Y., announced yesterday that they had filed a motion to dismiss the charges.

If the motion is approved, as expected, by Judge Richard C. Giardino of Fulton County, it will mark the legal end of a case that has attracted the attention of Asian-Americans around the country. But any celebration for Mr. Wong might be short-lived and bittersweet, since he is expected to be deported to China, meaning that his first taste of freedom in two decades would be not in the United States, but in Hong Kong or China.

Mr. Wong, now 42, was serving time for armed robbery when he was charged with fatally stabbing Tyrone Julius at the Clinton Correctional Facility in Dannemora, about 17 miles west of Plattsburgh. And though there was no physical evidence or obvious motive, Mr. Wong was found guilty based on the testimony of two witnesses and was sentenced to 25 years to life in prison.

Years later, Mr. Wong's case garnered the support of Asian-American advocates in New York City, who viewed his story as emblematic of a criminal justice system stacked against poor immigrants who barely speak English.

Subsequent articles in The New York Times and inquiries made by a Manhattan private investigator, combined with the reversal of testimony by one prosecution witness, also suggested that another inmate had killed Mr. Julius.

In the legal arena, though, Mr. Wong suffered setback after setback, none worse than a decision by Judge Timothy J. Lawliss of Clinton County Court in October 2003 that concluded there was not enough fresh evidence to merit a new trial, said one of Mr. Wong's lawyers, William E. Hellerstein, a professor at Brooklyn Law School.

But on Oct. 21, with Mr. Wong's legal options running out, a state appellate court unanimously overturned the conviction and returned the case to Clinton County Court, citing the reversal of testimony by a key witness, the lack of physical evidence and the insistence from former inmates and Mr. Julius's widow that Mr. Wong was innocent.

As a result, District Attorney Richard E. Cantwell of Clinton County, who did not handle the original trial, filed a 17-page motion yesterday to dismiss the charges.

In an interview, Mr. Cantwell - who is the third district attorney to handle the case - said that he still felt Mr. Wong's original trial had been fair. He also said that the remaining prosecution witness, a correction officer named Richard LaPierre, stood by his original testimony that he saw the stabbing from an 80-foot tower 120 yards away.

But Mr. Cantwell also said that there was a "ton of problems," especially the recantation of testimony by Peter DellFava, a former inmate and the disappearance of several items that had been gathered after Mr. Julius was attacked.

"It's done, it's over and that's the right thing to do," he said. "I think a jury will have a difficult time finding beyond a reasonable doubt that David Wong committed the murder."

Mr. Cantwell also noted that the Department of Justice had issued an order to deport Mr. Wong in 1994, meaning that he is scheduled to go from state prison to federal custody, whether he is freed or convicted again.

"Look, he has been incarcerated since 1983, and all he's doing is he's waiting to be deported," Mr. Cantwell said. "So what are we going to do? Keep him here forever?"

Mr. Wong's supporters, meanwhile, said that they were ecstatic and relieved that a case that they believed was a strong one from the outset had finally gone their way. But they acknowledged that they had sometimes worried that Mr. Wong would not prevail.

"It's gratifying," said Jaykumar A. Menon, one of Mr. Wong's lawyers, who works for the Center for Constitutional Rights in Manhattan. "This is Sisyphus triumphant."

The odyssey for Mr. Wong, a former Chinatown busboy who was serving 81/3 to 25 years for his part in the robbery of his boss's home on Long Island, began on a snowy afternoon in March 1986, when someone plunged a shank into Mr. Julius's neck. Of the 70 to 100 inmates in the area, only Mr. Wong and an inmate from Hong Kong, Tse Kin Cheung, were searched. Investigators found neither blood nor a weapon on either man.

After Mr. Cheung began writing to Asian-American community leaders, claiming that Mr. Wong had been framed, a group of New York City activists formed the David Wong Support Committee. And eventually, former inmates and others came forward to say that Mr. Julius was, in fact, murdered by a rival, Nelson Gutierrez, who died in 2000.