SANTIAGO DE MARIA, EL SALVADOR -- It has been nearly eight years since Luis Oscar Guzman died with nine of his teen-aged friends on a coffee farm near here, but the memory of that day still terrifies this town.

The secret is told in whispers even today.

Guzman, 19 at the time, was one of 10 members of a Boy Scout troop formed in the late 1970s by Hector Antonio Regalado, then a prominent dentist in this hilltop town 60 miles east of the Salvadoran capital. But these were not the same kind of Boy Scouts that Jose Napoleon Duarte, now president, had in mind when he founded the Boy Scouts of El Salvador in the 1950s.

Regalado, a small, soft-spoken man known for his extraordinary powers of persuasion, preached a rabid brand of anticommunism to his youthful followers. By the account of townspeople and two men who worked under Regalado, he trained the teen-agers in weapons and tactics, then sent them to kill Marxist-led guerrillas. The Boy Scouts of Santiago de Maria became one of the country's first death squads.

Then, on Dec. 27, 1980, according to the same sources -- who, however, acknowledge they were not present -- Regalado, fearing that the teen-agers knew too much and might talk, had them killed.

"We had the position and the power to denounce all this," Guzman's father said as he held his son's tattered death certificate, taken from an album of faded family pictures. Forcing back tears, he added, "Everyone knew what was going on, but we kept our mouths shut because we assumed the authorities were involved."

The story of Santiago de Maria's Boy Scouts is macabre even by the standards of El Salvador's notorious right-wing death squads, which claimed an estimated 40,000 lives during the early 1980s.

The account told by two former death squad members who worked under Regalado, and corroborated by townspeople, came to light in a four-month investigation of the death squads. It involved dozens of interviews with the pair, as well as with Salvadoran and foreign intelligence, security and military officials.

The inquiry shed new light on the clandestine groups' operations and their extensive links with the military. It also produced new information on the 1980 assassination of archbishop Oscar Arnulfo Romero, the country's leading human-rights advocate, and revealed how death squad leaders obtained the nation's most sensitive intelligence, enabling them to avoid capture and prosecution by reformist elements of the Duarte government.

The two former death squad members, Jose Hernan Torres Cortez, 33, and a man who spoke on condition that he be identified only by his old nom de guerre, Jorge, charged that former Army major and rightist political leader Roberto d'Aubuisson headed the nationwide death squad network, and that Regalado was his right-hand man.

D'Aubuisson, 45, the founder in 1981 of the rightist Nationalist Republican Alliance (Arena) political party and currently a member of the 60-seat National Assembly, denies any links to death squads. Regalado, who spends much of his time in Guatemala, could not be reached for comment.

In extensive interviews with two reporters, Jorge and Torres separately said they began working for Regalado in Santiago de Maria in the late 1970s and later for d'Aubuisson in San Salvador in the early 1980s. The two described the workings of the Secret Anticommunist Army, as their group was known, and the roles of participants they knew.

Because death squad operations were so compartmentalized, however, Torres and Jorge were able to describe only a small part of the entire picture. They had few details, for example, of the various other death squads they said operated under d'Aubuisson's overall command, such as the Maximiliano Hernandez Brigade, the White Hand and the Escuadron de la Muerte (Death Squad). They also showed little knowledge of the top echelon of the structure, said to be wealthy Salvadorans who financed death squad operations.

In congressional testimony in February 1984, Robert E. White, former ambassador to El Salvador, named six wealthy Salvadoran landowners, then living in exile in Miami, as the top death squad financiers. These "Miami millionaires," who lost great estates in a 1979 land reform program, "organize, fund and direct death squads through their agent, Major Roberto d'Aubuisson," White said.

The involvement of Torres and Jorge began here in the late 1970s, when they worked together for Regalado in a group called Regalado's Armed Forces (FAR from the Spanish).

"The FAR was a super-strong organization that was armed and virtually went around getting people from things like student movements and people they said were part of the subversion," Torres said. "We worked in the whole eastern region. What we did was take them from their houses, take them outside and kill them because they were subversives and were hurting the country."

A top military officer, who sat in on meetings where the formation of the groups was discussed, said members of the nation's oligarchy offered to fund and support the paramilitary squads if d'Aubuisson would lead them. These landholders felt the military was not responding strongly enough to the threat by leftist rebels, the source said.

In the late 1970s, El Salvador was sliding toward chaos. Rebellion was spreading through the rich coffee and cotton area around Santiago de Maria, and many residents were grateful to Regalado, whose armed followers protected the crops from rebel attacks and peasants seeking de facto land reform.

For many townspeople, the FAR might have passed into history as a necessary evil -- except for the Boy Scouts.

In March 1980, Jorge said, Regalado met with the leaders of his group for a barbecue, promising them they would soon "all be in heaven" with d'Aubuisson as president. Regalado then went to a farmhouse near the capital to meet with d'Aubuisson and other right-wing leaders to plan a coup against the reformist civilian-miltary junta then ruling, Jorge said.

But the coup plot was discovered in May 1980 and leaders of it briefly detained. Regalado fled to Guatemala. Eventually, deciding to cover his tracks, he ordered the deaths of 10 of his Boy Scouts because he feared they knew too much, Jorge and townspeople said.

Guzman's father recalled how a trusted aide to Regalado ordered the Scouts to go to a nearby coffee farm to await instructions. The aide then called in the Army, saying "subversives" had gathered on the farm, and the 10 were gunned down, said the sources.

Torres said he escaped because he was serving in the capital at the time as a messenger between Regalado and the National Guard. Jorge said he had left town several months earlier and heard of the killings when he returned later.

Torres said Army officers regularly lent helicopters to the FAR and National Guard to transport death squad members or evacuate their wounded. The civilian death squad leaders had regular access to regional and national headquarters of the National Guard and military, he said.

He said he participated in two death-squad killings, well-known in Santiago de Maria, under the direct orders of Regalado and the then National Guard sergeant, Juan Francisco Alvarado, who he said were commanded by d'Aubuisson.

Senior foreign and Salvadoran military officials confirmed that the Army at that time often operated in conjunction with paramilitary forces.

According to Torres and top military officials, officers or wealthy civilians known as padrinos, or godfathers, financed and otherwise sponsored the paramilitary death squads.

"They gave us money, arms, clothes, shoes and socks," Torres said. "They were called godfathers, but they were the highest level of the organization."Dentist as Security Chief

After the failed coup attempt, Regalado resurfaced publicly in 1982 as head of security at the Constituent Assembly. Arena had won the elections for the Assembly, and d'Aubuisson was voted president of the body.

Torres and Jorge then went to work at the Assembly, where they said Regalado took over the second floor, turning it into an arsenal and center of death squad activity. They said Regalado moved out in December 1983, when d'Aubuisson left his post to run in presidential elections.

As recounted by Torres and Jorge, the names of those who met with Regalado at the Assembly read like a who's who of death squad suspects named at various times by the U.S. Embassy and Salvadoran government. They included National Police detective Edgar Perez Linares, National Guard Lt. Isidro Lopez Sibrian, three civilian d'Aubuisson associates -- Antonio Cornejo, Fernando Sagrera and Francisco Guirola.

Lopez Sibrian, cashiered and suspected of participating in the killing of two U.S. land reform advisers in 1981, is currently jailed awaiting trial in a kidnaping case. Cornejo, d'Aubuisson's former private secretary, lives in Miami, where he is fighting extradition in the kidnaping case. Sagrera reportedly manages a shrimp business in El Salvador.

Guirola, who financed some of d'Aubuisson's activities, was arrested at a remote Texas airfield in 1985 on a charge of trying to smuggle out nearly $6 million in small bills. He was put on probation and fined $250,000 after a plea bargain, and after U.S. authorities charged the money was drug-related. He now reportedly is in business in El Salvador.

Perez Linares ran one of the most feared death squads, the Secret Anticommunist Army, Torres, Jorge and a top Salvadoran investigator said, and was a protege of d'Aubuisson when the former major was head of the feared national intelligence agency, disbanded in 1980. Later he was hired by the National Police, then under the command of Col. Reynaldo Lopez Nuila, whom U.S. officials hoped would clean up the security forces.

According to top military and police sources, Perez Linares captured three leftist guerrilla commanders and turned them, putting them to work for him. Perez Linares had sole contact with the three, called the Angelitos, or Little Angels. The three were instrumental in breaking the back of the guerrillas' urban movement in the early 1980s, helping to round up hundreds of their former colleagues, the sources said.

But there was another side to the operation.

The U.S. and Salvadoran governments were anxious to make the National Police a "clean" security force because d'Aubuisson and the far right had extensive contacts within the National Guard and Treasury Police. But with Perez Linares in their employ, the National Police also were effectively infiltrated, officials now admit.

Perez Linares, while working for Col. Lopez Nuila, also was being paid by d'Aubuisson and Regalado, by this account. He kept extreme right-wing leaders informed of any actions planned against them and used the Angelitos as an elite death squad, according to four sources with first-hand knowledge of the operations.

"I always wondered how d'Aubuisson knew exactly what we were doing," said one top official who worked closely with Perez Linares. The official acknowledged that the National Police paid the Perez Linares group's expenses throughout that time, but he insisted that he did not know then that Perez Linares was working for d'Aubuisson.

Perez Linares was dismissed from the National Police after Vice President Bush visited San Salvador in December 1983. Bush reportedly warned El Salvador's provisional president that the rightist killings were jeopardizing U.S. aid and produced a list of death squad leaders -- including Perez Linares -- whom the United States wanted removed. Bush's visit coincided with, but was not directly related to, the death squads' loss of the Assembly as a safe haven.

Jorge said he then moved with Perez Linares and the Angelitos to a safehouse owned by Guirola. D'Aubuisson and Regalado also maintained offices there, he said.

Jorge said he cooked, kept house and cleaned weapons for the Secret Anticommunist Army but left when they tried to force him to kill. He described in detail how he helped pace off the distance for a 1983 rocket-propelled grenade attack against the headquarters of the Christian Democratic Party and said the group openly discussed several other high-profile killings claimed at that time by the group.

The group would often celebrate a successful action by hiring expensive prostitutes, smoking marijuana and listening to pounding rock music for days at a time, Jorge said. Death of the Archbishop

Jorge also said that on three occasions he overheard the group brag about killing archbishop Romero in 1980, congratulating Perez Linares for being a sure-handed triggerman.

While saying mass in a San Salvador chapel, Romero was shot in the chest by a sniper who fired a single bullet through the chapel's open doors from a car on the street outside. The government last year made public a confession by the getaway car's driver, who said he never learned his passenger's identity. The driver charged that d'Aubuisson ordered the murder, but no legal action has been taken against the rightist leader, and the case remains unsolved.

"You should have seen how much blood came out of him -- that's because I got him right in the heart," Jorge quoted Perez Linares as boasting.

When Perez Linares and his comrades realized Jorge was listening to their conversation, he said, they put a gun to each side of his head and swore to kill him if he ever spoke.

While this version of the assassin's identity could not be confirmed, two Salvadoran officials who have investigated the murder called it credible. They said a police drawing of the triggerman, based on a description by the driver of the getaway car, closely resembled Perez Linares, and no other suspect.

The Secret Anticommunist Army's communiques were signed by "Aquiles Baires," who Jorge said was Perez Linares.

Jorge and Torres were members of d'Aubuisson's security group in the 1984 presidential elections. Jorge quit shortly after the elections, while Torres resumed work as an Arena security agent at the National Assembly.

With money growing short and their power waning, Perez Linares and the Angelitos turned to kidnaping wealthy businessmen to maintain their lifestyles, making it appear to be the work of leftist rebels, according to Salvadoran and foreign officials familiar with the case.

When the kidnaping ring was broken in April 1986, with the help of U.S. and Venezuelan intelligence experts, the group was charged with five abductions that had raised almost $4 million.

As police closed in on the kidnapers, one of the three Angelitos, Salvador Rodriguez, was killed May 1, 1986, in a shootout. The other two disappeared, and their whereabouts remain unknown.

Three rightists accused of taking part in the kidnaping ring are now in jail, and three other prime suspects who left the country are fugitives.

Perez Linares fled to Guatemala to avoid arrest in the case and was captured there secretly by Salvadoran National Police. While being brought back to San Salvador, he was shot to death, allegedly while trying to escape.

"He had to die," one top investigator said, tacitly admitting that Perez Linares was executed. "There is no way that {National Police} group could have let someone as knowledgeable as Perez Linares live to talk."

Washington Post correspondent William Branigin contributed to this article.