AFTER 14 years, 70,000 lives and $6 billion dollars in aid, U.S. hopes for a sustaining peace in El Salvador will rest on the shoulders of an attorney named Armando Calderon Sol. Considered a shoo-in to become president of that country in next Sunday's runoff election, the portly candidate personifies the new moderate image of ARENA, the ruling right-wing party that was founded by Roberto D'Aubuisson, the notorious leader of El Salvador's death squads.

Calderon, the popular and effective mayor of San Salvador, is the anointed successor of the current president, Alfredo Cristiani, who represents the enlightened, entrepreneurials who want to make peace with leftist guerrillas and build a modern country. But whereas Cristiani came from the country's modernizing business class, Calderon began his political career as a member of a seven-man, neo-fascist group under D'Aubuisson's guidance that supported death squad operations and engaged in political bombings.

American officials, who see El Salvador at a critical juncture in its struggling history, are publicly downplaying the significance of Calderon's ultra-right beginnings, while privately worrying that his rise to power will reactivate violent extremism from supporters who were with him in the trenches in the early '80s.

"A victory by Calderon Sol could be perceived as a pale green light to move ahead with violent activities," said one American expert who has investigated the death squads, "because he's always supported this. . . . . And even if he doesn't now, I don't think he has the moral fiber to stop it."

U.S. officials say that despite the appearance of a harmonious line of presidential succession within ARENA, there was a deep division between the Cristiani pragmatists trying to run the government, and Calderon and the D'Aubuisson faction, to whom Cristiani ceded control of the party. On several occasions officials said they strongly urged Cristiani to take more control of the party machinery but he wasn't interested. "They always said Calderon was going to be the next candidate," explained a former embassy official, "and we hoped they were kidding. He has all the worst elements of D'Aubuisson without any of his redeeming qualities."

The optimistic assessment is that Calderon, who helped to negotiate the 1992 peace agreement with the guerrillas, will continue along the course of rapprochement with the country's left that D'Aubuisson himself supported before dying of throat cancer.

"The country is on the brink of turning into a neat little place," remarked one U.S. official. "Let's hope that Calderon's insecurities don't make him try to show he's a macho man like D'Aubuisson was, which could lead him down some bad paths."

In temperament and physique, the pudgy, good-natured politician seems the polar opposite of D'Aubuisson, the tough charismatic major who led El Salvador's right in a bloody fight to hold on to power. Although U.S. officials have reported allegations that Calderon personally carried out terrrorist acts, these charges have not been investigated. However, it is well documented that Calderon was closely associated with those who did. During the years when U.S. intelligence reported that D'Aubuisson was running death squads out of the party's offices, Calderon was D'Aubuisson's trusted private secretary.

What engendered that trust, Los Angeles Times reporter Laurie Becklund and I learned in a year-long investigation into Salvadoran death squads in 1982, was that "Armandito" (as D'Aubuisson called him) had been a loyal soldier in a terrorist cell that followed D'Aubuisson's command.

The group grandiosely called itself the Salvadoran Nationalist Movement (MNS). They belonged mostly to the upper middle class -- what Salvadorans called "adjunct oligarchs" -- clean-cut young men often met circulating at Chamber of Commerce meetings. Calderon was recruited into MNS by its founder and leader, Alfredo Mena Lagos, the scion of a wealthy family in the shrimp business, who became one of D'Aubuisson's earliest backers.

But MNS members weren't your ordinary Jaycees. Their organization was laced with rituals and fascist doctrine. Members swore a secret oath, pledging their blood and their lives for MNS and the battle against communism. They admired Hitler's National Socialist party because it violently attacked communists, and they believed Hitler's only serious error was killing Jews. The MNS flag featured a steel-black sword symbolizing a will to fight.

The young counterrevolutionaries, explained Ricardo Paredes, who was in charge of MNS ideology and propaganda, initially spent "21 hours a day" trying to overthrow El Salvador's new civilian military junta, which took power in October 1979. That government, in the eyes of the young rightists, was virtually communistic because it was implementing a land reform program and included members of the moderate left.

"Armando analyzed from a legal point of view the things we were doing," said Paredes in 1982, adding, he "represented our soft line, you could say."

It was not until MNS met their "seventh member" that the group found its focus. One day while they were at Mena's San Salvador apartment, Paredes recalled, "Alfredo told us there was a major who wanted to talk to us." Mena introduced them to D'Aubuisson who had been forced to leave the army in November 1979. D'Aubuisson was seeking to link together dozens of groups of disaffected right-wingers into a popular counterrevolutionary movement.

Officially, MNS was an above-ground political organization that published declarations, solicited contributions, even announced its existence in a newspaper ad. But its political ideology was subordinated to creating a clandestine paramilitary organization. Its members explained to us that D'Aubuisson had studied political warfare in Taiwan and that his strategy focused on organizing civilians to provide the military with a flow of intelligence that could be used to eradicate leftist political organizations. The goal, they said, was to fight terror with terror. "It's not a legal war," said Paredes. "We don't want to fight a fair war. We have to go and beat their pants off."

D'Aubuisson immediately welcomed MNS into his inner circle. Its members were among the select few who had access to the intelligence files that D'Aubuisson had pilfered from the government and that served the movement as a central enemies list. The members of MNS smuggled weapons and other contraband in their private planes; they met with foreign advisers from the former French Secret Army Organization and the Argentine intelligence services to implement plans for a "dirty war" against the leftist and moderate opposition. D'Aubuisson's civilian network fed the names of suspected leftists to sympathetic members of the security forces. The effort contributed to one of the greatest slaughters in Central American history.

Several MNS members we interviewed admitted that when bombs began going off in San Salvador in early 1980, they participated in the terrorist campaign to destabilize the government and block agrarian reform. Their targets included the Jesuit-run Central American University, newspapers, radio stations, government buildings and churches, as well as leading leftists.

"I don't know if anyone was hurt," one of the bombers later told us. "I know some people left the country." To speed them on their way, MNS members composed phantom "death squad" communiques to drop at their targets. One member bragged to us about a black propaganda operation in which MNS created and planted fake leftist documents, falsely implicating Jesuit priests in the financing of guerrilla armies.

One of Calderon's compatriots in MNS was a young pistol-packing businessman named David Ernesto "Neto" Panama, who was in charge of "proselytizing and mobilization of personnel." According to the report of the U.N. Truth Commission, Panama also assisted death squads operating out of the intelligence section of the Salvadoran National Guard -- an office that one U.S. official characterized as "the most efficient killing machine in the whole National Guard." Today Panama is El Salvador's ambassador to Taiwan.

The commander of the National Guard intelligence unit at the time was a well-connected major with a long history of suspected death squad involvement named Mario Denis Moran. In 1982, MNS members told us that Moran was "of our line."

While Calderon's close and continuing association with the D'Aubuisson group is well-documented, his personal role in acts of violence is unclear.

One notorious death squad member, Moran's second-in-command, Lt. Isidro Lopez Sibrian, alleged in a recent declaration that he was present at a meeting when Calderon and others planned to bomb the Ministry of Agriculture. The alleged meeting seems to have stuck in the lieutenant's mind because Calderon apparently "was never taken" on paramilitary outings. But on this occasion, Lopez said, the future ARENA presidential candidate accompanied a man named Ricardo (Ricky) Valdivieso to the detonation point. Valdivieso is now El Salvador's vice minister of the interior and considered a frontrunner for a spot in Calderon's cabinet.

Lopez Sibrian also says that he was given information that Calderon was present at a meeting in early 1980 at which rightists purportedly decided to kill Archbishop Oscar Arnulfo Romero. Romero was assassinated in March 1980. Lopez Sibrian's statements concerning Calderon have yet to be investigated or substantiated.

A recently declassified State Department memorandum says that a Salvadoran army captain told U.S. officials in 1990 that he was present at a meeting in Calderon's house where D'Aubuisson ordered the kidnapping of the president of the Salvadoran Soccer Federation. The captain said that Valdivieso had collected the ransom. According to someone familiar with the meeting, the captain made it clear that this kidnapping would "implicate the next president of El Salvador." The information was forwarded to the State Department in Washington but apparently no further investigation was undertaken.

In late 1981, D'Aubuisson unified MNS and other groups of right-wing militants into the ARENA party. As one of the party's founders said, "You could say that MNS was the heart and soul of ARENA." From then on Calderon dedicated himself to party activities. In 1988 he ran for mayor of San Salvador and won.

U.S. officials say that although there is no smoking gun, they are concerned about the sheer accumulation of anecdotes linking Calderon to acts of violence. One says, "The fear is, you combine Calderon Sol and the people around him with the factious struggles currently going on between the different groups in the FMLN {the country's leftist coalition}, and it could all go up in smoke and set things down the wrong path."

A State Department official said that "it would be inappropriate to publicly comment on the elections before they occur."

"The people around Calderon Sol feel Cristiani went too far to the center and let the technocrats take over," said Salvadoran political analyst Leonel Gomez. "The Calderon Sol faction is more the people who were with him in the trenches. They're now claiming this is their turn in power. Make no mistake. They have made great changes since the early '80s. But there is a possibility of real disaster. This is the B-team taking over."

Craig Pyes is an investigative reporter based in New York. Laurie Becklund, a reporter in Los Angeles, contributed to this article.