It was an elegant, and by Mafia standards most unusual, vendetta.

Don Tommaso Buscetta, an old-style Mafia boss, had lost two sons, a brother and a nephew in the gangland warfare that flared up in this noisy, practically ungovernable city at the beginning of the decade. Fearing for his life after the defeat suffered by his clan at the hands of a rival "family," he fled to Brazil.

Buscetta's moment of revenge against his enemies came earlier this month. Acting on the basis of his 721-page "confession," Italian magistrates issued a total of 366 arrest warrants against alleged Mafia members in Sicily. Many of the suspects were already in jail. Others had fled. But 53 were rounded up by police in predawn raids in the Sicilian capital.

Practically all those denounced by Buscetta belonged to the "new Mafia" -- bands of ruthless gangsters from the mountains above Palermo who elbowed aside the traditional "godfathers" of the Sicilian Mafia during the 1960s and 70s.

"Buscetta had been defeated. He did not have any other way of getting his revenge other than by speaking to the magistrates. He had lost everything, including his own family and dearest friends. This was his vendetta," said Leonardo Sciascia, a prominent Sicilian who has written many books about the Mafia.

The uniqueness of this particular vendetta lies in the weapon chosen by Buscetta to strike back at his enemies: the Italian system of justice. Of all the rules of the "Honored Society," as the Mafia likes to call itself, the most inflexible has been the code of silence, or omerta. Disputes must be settled within the family -- never through the police.

Buscetta's decision to break omerta provides valuable insights into how the Mafia -- and, by extension, Sicily -- has changed over the past three decades. In the space of little more than a generation, the Mafia has transformed itself from a village-based power network to a multinational crime organization.

The same period saw a huge migration from the rugged and poverty-stricken Sicilian countryside to the towns along the seacoast. Palermo became one of the fastest-growing cities in Europe, more than doubling its population from 400,000 to more than 1 million.

With the rural migrants came the Mafia. In the years immediately after World War II, the organization derived most of its funds from administering the estates of the aristocracy for its own benefit. Today its biggest source of funds is narcotics -- a field that was anathema to the old-style "men of respect."

"In the old days, the Mafia was primarily interested in the exercise of power. Money was a means to achieve power. Today it is the other way round. The Mafia is a kind of international holding company which sees power as a way to amassing riches," said Ennio Pintacuda, a Jesuit sociologist who has studied the Mafia closely.

Italian investigators estimate that the Mafia's annual take in Sicily today is in the region of $1 billion. At least 60 percent of this sum is derived from trafficking in narcotics -- a large part of which ends up in the United States.

With the change in the Mafia's interests, according to Italian sociologists like Pintacuda, has come a change in its values and structures. As the Mafia has grown and amassed previously unimaginable riches, it has gradually lost touch with its rural origins. The organization's internal cohesion has declined as rival "families" feud for control of the immensely profitable drug trade.

The transformation of the Mafia was sealed at the turn of the decade by a dramatic upsurge of murders in Sicily: 48 in 1980, 101 in 1981, 151 in 1982 and 110 in 1983. The dead included magistrates and senior police officials -- among them Italy's chief anti-Mafia fighter, Gen. Alberto Dalla Chiesa, who was gunned down in a Palermo street in September 1982.

As Buscetta told the story in testimony to Italian magistrates, most of these murders were committed by the victorious families of the "New Mafia." The killing declined once they had consolidated their grip on Palermo -- but there are fears that it could rise again in response to Buscetta's confessions.

Last week police discovered the bullet-riddled bodies of eight petty criminals in a district of Palermo under the control of one of the "victorious" families. The incident was widely interpreted here as a gruesome reminder of the penalties of infringing the law of omerta.

"A dead body is the most effective message of all," said Franco Ferrarrotti, a sociologist who also has studied the Mafia closely.

The origins of the modern-day Mafia -- a word which means "place of refuge" in Arabic -- go back to at least the 11th century, when Sicily was conquered by the Normans. The term was used by Arab farmers who banded together in a mutual self-protection society against the new feudal landlords.

"The Mafia is a product of our history. For centuries, Sicily was dominated by distant powers. The state was always a long way away, but the Mafia was present -- and it developed into a crude justice system. The capomafia became the equivalent of the local magistrate," Sciascia explained.

The most effective blow ever struck against the Mafia was by Benito Mussolini, the dictator who refused to tolerate any challenge to his own authority. In the 1920s and 30s, tens of thousands of suspected Mafiosi were thrown into prison on the flimsiest evidence, tortured until they confessed and shipped off to grim penal islands.

Although suppressed by Mussolini, the Mafia was by no means crushed. Its chance came with the liberation of Sicily by the western allies in 1943. By presenting themselves as both antifascist and anticommunist, the surviving "men of respect" managed to win the confidence of commanders of the U.S. 7th Army.

This improbable alliance, in the opinion of many Sicilian historians, allowed the Mafia to more than recoup its losses under Mussolini. Aided by the Italo-American gangster Lucky Luciano, the Mafia quickly grabbed control of key sectors of the economy, including the trade in agricultural produce between the countryside and Palermo.

Most elderly Sicilians have memories of the archetypical Mafioso of the past: a poorly dressed, illiterate old man who would hold court in the main street of a village -- dispensing favors, settling disputes, wielding power. This image of a populist feudal landlord, who exploited his subjects mercilessly but was bound by a crude code of ethics, has now vanished.

The birthplace of the "New Mafia" was Corleone, a town of 11,000 inhabitants about 30 miles southwest of Palermo. It was there that a gangster named Luciano Liggio recruited a band of ruthless killers from shepherds frightened about losing their grazing pastures to farmers. After eliminating the traditional Mafia in a frenzy of killings, Liggio's band moved to Palermo in the late 60s.

Liggio's gang arrived in Palermo at a time when the city was undergoing an unprecedented building boom. There were bloody massacres as rival Mafia bands fought for control of the construction industry while Palermo expanded.

The battle over the building permits provided a foretaste of the even bloodier confrontation touched off by the prospect of huge profits from the narcotics trade. In testimony to Italian magistrates, Buscetta has accused "Liggio's followers" of unleashing an uncontrollable spiral of violence in a successful bid to win a monopoly in the production and distribution of heroin.

Buscetta has also accused the men of Corleone of responsibility for most of the killings of law officials such as Dalla Chiesa.

While ordinary Sicilians are skeptical that the Mafia can ever be entirely vanquished, Buscetta's confessions have been taken as an encouraging sign. They have pointed to serious cracks in an organization that has traditionally owed its strength to its internal cohesion. "This opens up new possibilities. Now that a Mafioso of Buscetta's rank has spoken out, others could follow his example," said Giusto Schiachitano, one of the small band of Sicilian magistrates who have waged war against the Mafia.

"I feel a little freer since Buscetta began to talk," said Vicenzo Noto, a Catholic journalist.

Luigi Colajanni, the regional Communist Party leader, said it would be a long time before what he termed the "suffocating power" of the Mafia ever disappeared.

But he added: "In the past Palermo never really spoke out against the Mafia. It simply suffered its presence. Now it has become part of the political agenda. It's as if a taboo has been broken."