XAPURI, BRAZIL -- A year and a half after gunmen shot down acclaimed Brazilian union leader and ecologist Chico Mendes outside his home in this small town in the Amazon forest, the accused killers have yet to stand trial.

The delay in bringing the case to justice has brought a storm of protest down upon Brazilian officials from environmental and human rights groups within the country and abroad, and left a pall of fear and intimidation over this once-placid town on the Acre River.

"It's starting all over again," said Ilzamar Mendes, Mendes's widow, standing on the dirt street in front of the house with fading blue and pink paint where her husband was killed by a shotgun blast three nights before Christmas in 1988. "The same climate of fear and threats that led up to Chico's death is back."

It was in Xapuri that Mendes mustered rubber tappers into a powerful rural union and blocked area ranchers from razing the region's rubber and Brazil nut forests for cattle grazing.

Shortly after the murder, police arrested a farmer, Darly Alves da Silva, and his son, Darci Alves Pereira. Darci is charged with carrying out the crime and his father with planning it. A third man, Jardeir Pereira -- Darly Alves's nephew and still at large -- is charged with participating in the killing.

Mendes's murder thrust this sleepy region of the Brazilian Amazon into the glare of international attention, and the mounting tensions in Xapuri have again turned this westernmost Brazilian region into a lightning rod for international criticism.

Most of the heat has fallen upon the chief justice of the Acre State Court, Lourival Alves da Silva. In a recent interview in Rio Branco, the state capital, Silva shoved aside a pile of court papers and lifted an olive cardboard folder, fat with letters and telexes. "I call this my green file," Silva said, thumbing through the wad of dispatches from more than two dozen environmental and human rights groups, from London to Buenos Aires.

Nearly every day, yet another cable from another environmental entity arrives at the state court building, demanding that justice be done.

"The people don't understand that this is the normal delay for a case as complicated as this one," Silva said in an interview. He pointed to a tower of bound legal papers. "The {Mendes} case already fills seven volumes."

In recent weeks, Silva has fielded a volley of legal maneuvers filed by attorneys for the Alves family. The motions have shuttled this case between courthouses in Xapuri and Rio Branco. Last Tuesday, the judge denied the latest defense motion to drop charges, thus clearing one more obstacle to the trial.

Now, 18 months, more than a dozen motions and 1,500 pages later, defense lawyers are expected to make a final appeal to the Supreme Court in Brasilia, the nation's capital, demanding the case be dismissed for lack of evidence. This week the court in Xapuri will begin a session that normally lasts until July 15.

The National Council of Rubber Tappers, the union Mendes founded in 1985, has voiced fears that all the legal maneuvers are really meant to block the case from ever coming to trial. They said they also suspect state officials of dragging their feet in hopes of delaying the controversial trial until the next session, in December, safely after state and local elections in October.

Judge Silva and the judge of Xapuri, Adair Longuini, have filed in and out of the governor's palace to discuss the progress of the Mendes case in recent weeks. "This is," a judicial aide said in a hushed voice in the Acre court building, "an extremely delicate affair."

Council members say a delay could embolden area landowners, whom they accuse of masterminding and "ordering up" the Mendes murder, and abet a "reign of terror" already said to be gripping Xapuri.

Terror is not what one expects in this bucolic town, where residents sit out on the sidewalk under the shade of mango trees and fan themselves against the heat of the Amazonian summer. Yet townspeople speak of a climate of fear that gnaws at the peace of Xapuri. Behind it, they say, is a barely veiled effort by powerful ranchers to intimidate witnesses, harass union members and generally show who is boss here.

In Xapuri, a compact town of 16,000 inhabitants, a few miles of pavement and no newspaper, rumors run free. One recent story told of a "death list," naming 25 Acre rubber tappers marked to die. Heading the "list" is Mendes' outspoken successor, Osmarino Amancio Rodrigues, president of the rural union in nearby Brasileia. He never walks alone or sleeps in the same place two nights in a row.

Another story told of a plot by landowners to spring the Alveses from jail. Still another reported a recent murder at the Alveses' farm, the Fazenda Parana, to silence a farmhand who supposedly knew too much. Alvarino Alves, Darly Alves's brother and alleged accomplice in the murder, has managed to escape all police dragnets but is rumored to be back in town, orchestrating the intimidation.

Police have been unable to confirm these stories, but as the trial session draws nearer, tensions have mounted. Ilzamar Mendes said Darlyzinho, another of Darly's sons, physically assaulted her in broad daylight and, just a week ago, showed up outside her home late one evening, displaying his revolver. Xapuri Judge Longuini has received so many telephone threats that his home phone no longer receives calls.

Many Acre residents now assert that only a speedy trial can restore calm in Xapuri. Some go even further. "All I know is that if they let that man go, the stores are going to shut down and the customers are going to disappear again," said one shopkeeper, recalling the wave of fear that swept the town immediately after Mendes's death.

Nilson Oliveira, the police inspector who conducted the murder investigation, echoed that sentiment. "A guilty verdict would be a fundamental first step to making Xapuri once again a place run by the community instead of the ranchers."

The Alves' lawyer may still file other motions to delay the trial or reduce the charges against the defendants. A likely move is a request for a change of venue, to remove the case from the politically loaded atmosphere of Xapuri to a neutral area, such as Rio Branco or Brasilia.

However, Judge Silva said that such eleventh-hour requests are not likely to be granted. "The case documents are filled with enough evidence to back the Xapuri court's decision to send this case to trial," Silva explained. At the latest, Silva predicted, the case could be scheduled in July or even in August, in a special court session.

"All the instruments available to the justice system are being used to expedite this matter," he said. "This is a priority case. Our intention is that it be judged in the coming session. There will be no postponement." Margolis, a Washington Post special correspondent, is reporting on the Amazon frontier for the Alicia Patterson Foundation