Sitting on rough pews under the thatch roof of a makeshift Evangelical church, Siegfried Williams and a group of fellow Miskito Indian leaders poured out a tale of horror and death to explain their presence in this grim, overcrowded refugee camp, 20 miles north of the Coco River border with Nicaragua from where they fled.

"The Sandinistas have assassinated our men, raped our women and even buried our people alive," charged Williams, a gaunt, mustached Indian in his late thirties, as the other Miskitos nodded in agreement. "We are here because to have stayed home would be to have died."

Pressed for precise details about their charge of Sandinista repression of their people, Williams and his friends invariably talk of the Dec. 23 "massacre" of 105 Miskitos in the Coco River town of Leimus.

Theirs is a harrowing tale and the basis of Secretary of State Alexander M. Haig Jr.'s charges before a House subcommittee on March 4 that Nicaragua was pursuing a "genocidal" policy against its unfortunate Miskito Indian minority.

The account Williams calmly gives a visitor is also the story of a massacre that some well-informed people here and elsewhere in Honduras say may never have happened--at least not in the way the Miskito refugees have now enshrined it in their oral history nor in the manner that Haig described it for Congress in testimony based on refugee interviews by officials from the U.S. Embassy in Tegucigalpa.

Certainly something ugly--and deadly--did occur in Leimus that night. People died, houses burned and, since then, the town has remained abandoned, like dozens of other Miskito communities along the Nicaraguan shores of the Coco River.

But following a day of interviews with Miskito refugees here in Mocoron, a camp that has swelled from 200 at the beginning of the year to more than 7,800 now, and talks in Tegucigalpa with Honduran officials, foreign relief workers and other officials involved with the Miskitos and knowledgeable about tensions along Honduras' border with Nicaragua, just what happened in Leimus and at whose instigation remains a subject of debate.

The expanding political and military disputes of Central America provide sharp reminders that in remote zones of conflict, confusion and contradictory accounts frequently surround what should be the most straightforward of events. That is certainly the case in Leimus.

In Leimus there are two versions of what went on--the much publicized and narrated official version alleging an unprovoked Sandinista massacre and another, given credence by many sources interviewed in a visit in the area, alleging the shooting was not unprovoked but triggered by a night raid across the river on Leimus by dissident Miskitos armed and trained in Honduras.

The official version of the massacre, as narrated now by Williams and his friends in Mocoron, first appeared in what was presented as an official Honduran government communique published by the Tegucigalpa newspaper El Heraldo, which is reputed to have close ties to Honduran military intelligence. The communique, whose official nature is questioned by other editors in Tegucigalpa, was not given to any other newspaper. It quoted a Honduran Army sergeant from a local garrison on the north shore of the river across from Leimus.

Sgt. Pedro Moreno Cotto, according to the paper, reported gunfire at Leimus that night and people fleeing across the river into Honduras, some wounded in the water as they swam to safety. As Williams and his friends tell it, the Sandinista army "inexplicably" came into town in force late, ordered everyone to evacuate their homes, then after nightfall rounded up the men and marched them off for execution.

Seventy were killed on the outskirts of town, according to Williams, many of them on the banks of the river, their bodies left to drift with the strong currents toward the Caribbean Sea. By Williams' count, 35 others were ordered to dig their own graves, then shot as they stood in them, those who had not died being buried alive.

Williams' story, told with much back-and-forth comparison of approved detail in the Miskito tongue among the five other Indians who share in the leadership of this refugee city, has clearly been through many tellings to visitors, whether journalists, U.S. diplomats from the capital, relief workers from Europe, or travelers such as the representative of the Mohawk Indian nation who came early this month for a two-day visit.

The six-man leadership council, none of whom was at the site of the incident, presented two Miskitos who were residents at Leimus who told me, through their leaders, who were translating from my Spanish into Miskito, identical stories. Under questioning, these Miskitos would give no personal details or experiences of the incident that could have given their counts greater credence.

A different story was told by two Miskitos who talked with me alone, away from the official leaders, after I was led by others to a thatch refugee hut on the edge of the sprawling camp. Their story was corroborated later by other reliable sources acquainted with events along the Coco River in the past year.

That story speaks of the events at Leimus not being a massacre by Sandinistas bent on Indian murder. Rather the sources said that a group of armed Miskitos, trained in Honduras along with other anti-Sandinista Nicaraguan refugees at a camp called Rus Rus, had set off in a fleet of canoes under the cover of darkness to raid the small Sandinista garrison at Leimus.

According to these sources, who included an officer in the Honduran armed forces who was sent later to investigate the events, the Miskito-led anti-Sandinista raiding party was ambushed on the river as it beached its canoes on a sandbar outside of Leimus. The shooting that was heard through the night, according to this account, was a result of a fire fight between the two armed groups and the bodies that later floated down the river were those of dead raiders who were killed as they sought to escape from their canoes.

The fierceness of the battle, coming as it did after months of similar raids against Sandinista outposts along the river from armed Miskitos in Honduras, sent panic among residents of Leimus and other communities along the river.

Already warned by Sandinistas that they would clear a security zone along the river if the clashes continued, most residents, including Williams who lived in nearby San Jeronimo, fled to Honduras, beginning the wave of refugees that has reached a total of 10,000 of the estimated 120,000 Miskitos of Nicaragua. Many of those who did not flee north to Honduras have since been rounded up and force marched south to camps in the Nicaraguan interior.

This story parallels the account released by the Sandinista government in Managua last month that detailed two years of alleged border attacks by dissident Nicaraguans that the Sandinistas say are trained and based in Honduras and funded by the Central Intelligence Agency.

In December, Nicaragua said, 21 persons died along the Coco River and four were wounded, one of them a Cuban technician sent to work in this previously neglected, isolated and underdeveloped zone of jungles, savannas and marshes.

Many Miskitos, when questioned, acknowledge that some of their number, most notably a group of 300 to 500 who support exiled Miskito leader Steadman Fagoth Muller, have been trained and armed in the past six months to harass the Nicaraguans.

Fagoth, in an interview in Washington in February, admitted that his followers were armed and prepared to fight the Sandinistas "in a way." He insisted, however, that his fight against the Sandinistas was "defensive."

Fagoth, 29, an engineering student, had been a supporter of the Sandinista revolt against the dictatorship of Anastasio Somoza before fleeing into exile last year. While he is generally respected for having stood up for Miskito rights against the Sandinistas, he is not considered the Miskitos' "maximum leader," which he has claimed to be on his forays abroad, based on his previous leadership of the Misurasata council, which is no longer functioning.

In Mocoron, the leadership of the Indians revolves around Williams' six-man council, which acknowledges Fagoth as well as others of the Misurasatas' former 11-man ruling council as part of the tribal leadership. But there is a major split among Miskitos, with some following Fagoth and others not.

The Sandinistas say they genuinely thought that by spreading the revolution to the Miskitos, long-isolated and ignored by governments in Managua, they would be making a major contribution to the development of the sparsely settled eastern part of their country.

Fagoth was picked by the Sandinistas to lead an Indian organization in the region called the Misurasata. He rallied the Indian organization to demand both greater autonomy and a share of any mineral or timber wealth exploited in the region by the government.

Even sources sympathetic to the Managua government feel that the Sandinistas' chief error was to rush in with a Spanish literacy campaign, often taught by Cubans, which was taken by the Miskitos as an effort to obliterate their traditional language and culture. Troubles between the Miskitos and Sandinistas began in September 1980 when 50 Indians were arrested after a general strike.

The Sandanistas were steadily building up their military presence in the area on their Atlantic coastline that is close to Cuba. Cuban military advisers are reported by diplomatic sources to be active around Puerto Cabezas and an airfield that could take Migs from Cuba has recently been expanded there.

Fagoth's incendiary eulogy for an Indian fisherman killed in Puerto Cabezas by Sandinistas sealed his break with the Sandinistas. On Feb. 19 he and 32 other Misurasata leaders were arrested. Later he was released, fled to Honduras with some 300 followers and began plotting his campaign to fight the Sandinistas, joining with other dissidents gathered on small farms and in villages along the Honduran border.

Diplomats in Managua said that even before the clashes between Sandinistas and Miskitos began, the government had plans to begin resettling Miskito Indians as part of an economic development plan in the area. The clashes along the Coco River only accelerated the process, showing a need to clear a security area along the frontier, which is as isolated on the Honduran side from the Honduras capital as it is on the Nicaraguan side from Managua.

Fagoth also occasionally visits this refugee city to talk to Miskitos about his trips abroad, mostly to Washington, where he has gone at least twice, seeking recognition of his cause and support for his continuing opposition to the Sandinistas.

He makes his base these days some 10 miles away in the Honduras military camp next to Rus Rus, which has been put off limits to outsiders by its local commandant and which is generally said by Miskitos and others here to be a place where Fagoth and his Miskito raiders are being trained.

"The sad case of the Miskito is really that they simply got caught up in something much bigger than they were," said one relief worker here who has worked among them for almost six months. "There is no doubt the Sandinistas made enormous blunders in trying to bring the revolution to them, giving no recognition to the Miskitos' traditional culture."

"This certainly led to tensions, the split with Steadman, arrests, demonstrations and more blunders," he said. "But who shot first is a question that we may never really know."