The men with the machetes brought 14-year-old Rufina back to her mother and the rest of the huddled captives. She was limping and in tears. The other women knew she had been raped, and what was going to happen next, as they sat tied in the dark and dust near the rank stream called El Guayabo.

They were all about to die.

In these last moments Rosa Amalia, 21, who also had been raped, still thought of her young children back near the capital. Their father was gone, too. He, his brother, his father and his uncle had been dragged away in the night a week before and "disappeared."

Rosa Amalia knew some of her captors, and she pulled money from her dress. One of her captors was to testify later that she asked one of the men if he could do her "the favor" of giving the money to a friend, "that he might go to where my Mama is and turn it over to her that she may buy milk for the baby girl," she told him, then added one last request.

"Say not to look for me," she said.

On the night of March 4, Rosa Amalia Beltran and 10 of her or her husband's relatives were killed in a savage, methodical onslaught of gunfire, rifle butts and long knives wielded by the quasi-military government garrison of this and nearby settlements. Among the dead were four of her brothers, her young sister-in-law, her mother-in-law, her dead husband's four younger brothers and sisters, including Rufina. Eight others, including five additional children down to the age of 2, also were killed. Their bodies were buried along the banks of the creek not far from the shores of Lake Ilopongo.

Human rights groups have charged Salvadoran government forces and their paramilitary allies with carrying out massacres on a routine basis, accounting for a high but undetermined number of the tens of thousands of lives lost in El Salvador's political violence during the past three years.

Usually there is no evidence but the dead or the documentation supplied by organizations sympathetic to the left to show how the killings come about. Otherwise the slayings are not seriously investigated.

In this case, however, the alleged murderers made two serious mistakes: They assaulted the immediate family of a Salvadoran National Police officer and in the confusion of the attacks they allowed one of those relatives to escape and tell the tale.

As a result, for the first time in the memory of several Salvadoran court officials, government military and paramilitary agents, including a member of the Treasury Police, have been detained in connection with the murder of Salvadoran peasants believed by the accused to be "subversives."

The government announced the arrests, but it has not released background information. As prosecutors build their case, however, an anatomy of the attack has emerged in 47 black-and-white photographs of the grave and its contents, in sworn complaints and depositions and other court documents held at the Justice of the First Instance in the town of Cojutepeque.

The court papers show the deadly intimacy of the violence in this country, where a civil war is being fought between Marxist-led insurgents and soldiers whose traditions have included an unrestricted license to kill in the name of anticommunism. For the most part there are no battle lines, and in sometimes clandestine, sometimes almost casual operations, peasants are murdering peasants because of suspicions, for personal reasons, or because they believe they were told to do so.

In this case, and under Salvadoran law, which is radically different from that of the United States, 12 of the suspects could be considered arraigned, although the gravity of the charges to be brought against them is not yet clear. Most of the 13 men who have been detained pleaded not guilty, then proceeded in their depositions to outline their participation in the crime. Their defense, in most instances, is that they were following orders.

The Treasury Police officer is in the process of being dismissed from the service so he can be tried in civilian courts. Meanwhile, according to an official letter to the court, he is being held under arrest in the police headquarters in San Salvador.

Adjoining Palo Blanco at the edge of Lake Ilopongo is the settlement of San Augustin, where a man named Moises Montenegro, 46, commands the town's "military escort."

Such loosely organized, nonuniformed groups exist in most villages in El Salvador. Theoretically they are made up of armed forces reservists under military discipline and their commander is usually an active-duty noncommissioned officer, although there is no reference in any of the documents to Montenegro's rank or current military status except to call him the commander of the group.

Many villages traditionally have had other armed, vigilante-type squads as well, known as cantonal patrols under the civil jurisdiction of the local mayor. In the past two years these have been largely replaced or transformed into "civil defense" units under military authority.

During the 1970s many members of these same groups formed the core of ORDEN, an armed, right-wing political and intelligence organization held responsible for much of the repression in the country before being officially dissolved in the wake of the reformist October 1979 coup. At the time, ORDEN's strength was estimated to be at least 80,000 men.

In one form or another these semi-military patrols date back to the 1932 massacre of 30,000 people that ended a communist-led peasant revolt. Since then they have been charged with keeping an eye on subversion, and in many cases they considered their mandate to be the elimination of subversives wherever they were suspected to exist.

"These people live and breathe in their communities," said one foreign analyst who has studied the paramilitary organizations. "But they're people who have chosen sides and taken up arms. This is a very complex and personal thing. Often, lines of authority are crossed, and crazy things happen."

Their members are rarely paid a salary but are imbued with the authority of the government and are permitted to carry weapons and sometimes issued cast-off military equipment. They also are allowed in some cases to collect "voluntary contributions" from their neighbors.

As the war has grown, the members of these groups have become the frequent targets of rebels and are often killed outright by the insurgents if caught. The paramilitaries have also tended to blend more with regular troops in areas of regular fighting, if not as combatants then as guides and informers.

The 2,500 Treasury Police are the smallest and the most notorious of El Salvador's three major uniformed security forces involved in counterinsurgency operations. Along with the National Guard and, to a lesser extent, the National Police, they work closely with the paramilitary groups in the countryside and are known for their intelligence apparatus.

In recent months there have been serious frictions, however, as the National Police under Col. Carlos Reynaldo Lopez Nuila have worked hard to improve their domestic and international image for standards of professionalism and respect for human rights, while the Treasury Police, under Col. Francisco Moran, continue to find themselves implicated in the kinds of incidents that have given the government here an infamous human rights record.

Roberto D'Aubuisson, a cashiered right-wing major who has emerged as one of the most powerful individual politicians in the country since last Sunday's elections, referred to members of these quasimilitary organizations as "anonymous heroes" during his campaign.

Abuses by government forces have been cited by guerrillas as a primary reason that only "armed struggle" can reform Salvadoran society, even as the guerrillas frequently have provoked excesses on the part of security forces.

The United States, nevertheless, has made it clear to the current government of President Jose Napoleon Duarte and to the contenders for power since the election that the "process of control" over such abuses--a process Duarte maintains has been underway for two years--should continue regardless of who emerges in control.

Most of the men, women and children killed here came originally from a collection of little hamlets to the north of San Martin, just off the Pan American Highway about 10 miles east of the capital.

Those villages, just on the edge of territory claimed by guerrillas operating from bases on the Guazapa Volcano, are the scene of frequent firefights, ambushes and government "cleanup" operations. In the last two years many families, especially those suspected of sympathizing with the left, have fled to live either with relatives or in refugee camps elsewhere in El Salvador.

When the Beltran family left that area, some went to Soyapongo, a working-class neighborhood on the edge of the capital, while Rosa Amalia Beltran came down across the Pan American Highway to the normally peaceful shores of Ilopongo here with the family of her husband, Antonio Montano Martinez.

But any kind of stranger is suspect these days and potentially fatal rumors spread quickly.

On the evening of Feb. 27, Moises Montenegro was visited at his home in San Agustin by a Treasury Police officer, Manuel de Jesus Bolanos, who is Montenegro's nephew, according to one deposition.

Bolanos said that a "collaborator" had investigated some people living in Palo Blanco and they were subversives. Since Montenegro said he could not go at the moment, Bolanos took a few men and set out for the village, according to Montenegro's statement.

The deposition of one of those paramilitaries details the interrogation that went on when the four suspects--Antonio, his brother Ascension, his father Jose and his uncle Timoteo--were dragged from their houses and their thumbs tied behind their backs as they were taken to the edge of the water.

"Bolanos asked the captives if they had belonged to any subversive groupings and the four unknown men answered that they had participated in activities to which Father Rutilio Sanchez, parson of San Martin, had entrusted them," says the statement of Cleotilde Lopez Guzman. The statement added that "by the public voice the declarer knew that Father Sanchez was of the FPL," the guerrilla faction called the Popular Liberation Forces.

The four men were then killed and in two canoes were rowed out to the deepest part of Lake Ilopongo where stones were tied to their feet and they were dumped, according to various depositions.

One of the paramilitaries involved in the operation told Montenegro the next day that even though the four had fled to Palo Blanco they "certainly" had been subversives because of their connections with the priest, according to the court records. He said that in any case "their women were still subversives because they frequently went to the village of San Jose Segundo to wash the clothes and make food for subversives."

According to Montenegro's statement this paramilitary said that Treasury Police officer Bolanos had told the group to get rid of the women in the same way the men had been handled.

On the morning of March 4, Montenegro and four of his men went to the local commander of San Pedro Perulapan, Treasury Police Sgt. Juan Lovato Bolanos, who is not known to be related to Manuel de Jesus Bolanos. They told Lovato Bolanos about the deaths and said they believed they were supposed to go kill the women, according to Montenegro's statement.

Sgt. Lovato Bolanos said he would investigate the names of the women, according to Montenegro's deposition, but it appears that Montenegro and the others took this as a signal to go ahead. Montenegro would later show several witnesses a piece of paper that he claimed was an order from the sergeant. But those people are illiterate and none can say for sure what it was or said.

In Palo Blanco, meanwhile, Rosa Amalia was preparing to leave. She had gone to her mother's home in Soyapongo after Antonio disappeared and her mother had "ordered" five of her brothers to go to Palo Blanco and move her out. Jose Medardo, another brother who is a National Police officer, stayed behind, but his wife Esperanza Alas, 17, decided to go along.

By late morning March 4, most of Rosa Amalia's things were gathered under the broad shade of a large amate tree looking down on the lake a few hundred feet below. Esperanza and Rosa Amalia decided to go look for a man named Nicolas, who owned a truck, and who--apparently unknown to them--is the brother of Moises Montenegro.

The two women were gone so long that their brothers eventually got worried about them, but they finally came back in the bed of Nicolas' gray Datsun pickup. They had been stopped on the way back by Moises and some of his men, according to various depositions, and when they got to the tree an unnamed man who lived near the tree took Nicolas aside for "a drink of water." Nicolas, who presumably had been informed in these conversations that something was up, soon found excuses not to transport Rosa Amalia's belongings.

The family did not realize it yet, but they were already captives.

When three of Rosa Amalia's brothers decided to take a trail to a main road and find other transportation they heard a voice saying, "Hold those there!" In a moment they were confronted by four men.

"If you are the authorities, why don't you identify yourselves?" the one survivor of the attack, Jose Hector Beltran, remembers demanding. But the men only answered, "None of that, this is the commander's thing," and the three brothers were forced to return to the amate tree.

There they found their family, along with several other people, being held by men armed with machetes. About an hour later, according to the surviving witness' testimony, seven men armed with shotguns and rifles arrived as well. One of these was Moises Montenegro, the witness said, and Montenegro's men also testified to his presence there and at the subsequent events.

But Montenegro claims that having been to Palo Blanco once in the morning ("We're going on a hunt," one of his men remembers him saying), he then left his men to do their business while he went fishing.

It was a long and desperate afternoon for the captives. One of the peasants who lives nearby was interviewed by reporters this week and said that the women were crying and pleading with their captors.

Some residents of the hamlet tried to help.

"There were people who said they the military escort should not be doing this," the peasant remembered. "But it was dangerous. The commander said he had an order and he didn't pay any attention. People said that to kill such people would not be correct, that they should be handed over to the higher authorities but not be killed. But they couldn't convince him."

The peasant said he remembered one woman crying, "Please, sir, don't kill me. I'm the wife of a policeman." And the peasant remembers the reply, "Those are lies."

The people of the hamlet did not intervene much, however, according to the peasant. "In these delicate times," he said, "a wrong word can bring you to a bad end."

The members of the "military escort" had been sitting on the roots of the tree talking in low voices. According to some of the statements, some of the members shared reservations about what they were doing, but the commander, Montenegro, insisted on going ahead.

At about 7 p.m., according to various depositions, the women and children were tied by their arms, the men already having had their thumbs bound behind their backs, and they were marched about two-thirds of a mile to the little ravine formed by the Guayabo.

Four men were assigned to dig a grave, while others, according to their depositions, were told they could use the women as they saw fit. According to the depositions, six men, including Moises Montenegro, participated in the rape of Rosa Amalia, Esperanza Alas and 14-year-old Rufina. A cursory examination made later by judicial officials indicated that Maria Erlinda, 12, a member of another family also taken along, was raped, along with her 7-months-pregnant mother, Melida Romero, and Salvadora de Jesus Pichinte, 30, who was three months pregnant.

By about 10 p.m., the three oldest Beltran brothers were taken a few hundred yards away from the rest of the group by three members of the patrol, one of whom, called Ulises Rosales, appeared to be drunk, according to the court papers and survivor's testimony.

At first the brothers were ordered to lie face down on the ground and the armed men began to beat on them with the butts of their rifles, saying, "Now you will respect the armed forces" and demanding to know, "Why did you go with the guerrillas," according to the survivor's testimony.

"You're sinners and you are committing a sin," Jose Alberto, 18, replied.

"You're in the hands of the armed forces, so you've got nothing to say," he was told.

The brothers were told to line up. They were about to be executed.

At that moment, Jose Armando, 25, an evangelical Christian, said "If this is the last day I'm going to live, I'm going to give thanks to Christ," and threw himself on his knees.

Jose Hector worked his thumbs free and, in the confusion caused by his brother, took off running to hide in the bushes until the first light of dawn. Then he made his way back to Soyopongo to tell his mother and his brother the National Policeman what had happened.

Two days later, Officer Jose Medardo Beltran and his surviving brother returned to the scene, which peasants nearby described as "rivers of blood" around the grave. Twelve members of the patrol were picked up that day, including Moises Montenegro, and a few days later Treasury Policeman Miguel de Jesus Bolanos was also detained, according to court documents.

The village of Palo Blanco is all but deserted now. The residents fled in fear of vengeance from one side or the other, according to one of the few men still here. When the surviving Beltrans came back with squads of National Police and forced the members of the patrol to dig up the corpses, "They went around very violently," the peasant recalled, adding, "There was a reason."