`I'm not a spy . . . I'm not a grass either . . . I was a mafioso and I have done many wrong things for which I am willing to pay, in full, my debt to society."

At about 12.30 a.m. on July 16th, 1984, in the stifling heat of a small office in the Criminalpol headquarters in Rome, ex-Mafia boss, Tommaso Buscetta started to sing. Buscetta, otherwise known as Don Masino, began his collaboration with the state by uttering the above words to a then little-known, Palermo-based investigator called Giovanni Falcone.

Buscetta knew only too well the significance of his decision to turn state's witness, thus breaking the code of omerta that had only rarely been broken before and never by a godfather as powerful as himself. He knew this was a significant moment, both for himself and for Falcone.

Leaning forward in his chair, he said to the young investigator: "First, they'll try to kill me, then it'll be your turn. They'll keep trying until they succeed."

The Mafia did, of course, succeed in killing Giovanni Falcone, blowing him up in a bomb attack in May 1992. Ironically, Cosa Nostra failed to kill Don Masino. The man who has long been known in Italy as Il Primo Pentito (the first turncoat) died on Sunday at the age of 71, killed not by the bullet of a professional hit man but rather by lung cancer.

He died in Florida, where he had lived under the auspices of a witness protection programme for most of the last 14 years. To his neighbours in the US and to the doctors who treated him, his name was Roberto. Typically for a man who had lived a cloak and dagger existence, details of his death were not released for two days.

A convicted mobster, Tommaso Buscetta cut a larger than life figure. A confirmed womaniser, he was married three times in three continents while he also had numerous affairs. His treading of the primrose path of dalliance earned him disapproval within the conservative world of Cosa Nostra.

Boss of Bosses and arch enemy, Toto Riina, once said to him, in reference to his libertine lifestyle: "You don't know how to behave, Buscetta. You're not a serious person."

Toto Riina was wrong. Tommaso Buscetta proved to be a very serious dude, indeed - first as a big-time, drug dealing mobster and then, of course, as the man whose collaboration with state investigators was to change the whole impact of Italy's previously hesitant fight against organised crime. Buscetta's testimony was a key element in the state prosecution's case at the 1986-87 Maxi Processo in Palermo which resulted in prison sentences for more than 300 mafiosi in relation to 121 murders and other crimes.

Buscetta's life as a mobster began early in wartime Palermo when, at the age of 16, he was hired to muscle into the black market for flour. Throughout the 1950s and into the 1960s, he was heavily involved in cigarette smuggling, apparently organising his consignments of Camel and Pall Mall from from the Bar Commercio in central Palermo.

Those, of course, were different times, an era when the word Mafia never appeared in Sicilian newspapers and an era when Don Masino, in order to reclaim his passport - withdrawn because of criminal convictions - merely wrote a letter to the Palermo Questura, asking for a new one. It duly arrived, permitting him to globe-trot through North and South America on "family business" using names that varied from Mario Conserva to Manuel Lopez Cadena to Roberto.

Arrested on Brooklyn Bridge in New York in June 1970 on Mafia charges, Buscetta made one effective phone call from the police station. Within hours, bail of $75,000 had been paid on his behalf. Two years later, however, things did not work out so nicely when he was arrested in Brazil on drug trafficking charges. Extradited to Italy, he was to spend much of the 1970s in prison in Palermo and then Turin before escaping, again to South America after "surprisingly" being granted house arrest by a Turin court.

The next few years, however, were to radically change Buscetta's life. While he was in Brazil, his family became involved in bitter gangland warfare in Palermo that saw his brother, a son-in-law and two nephews killed.

Tired of life on the run and terrified for his own safety, he started to reflect on his future. When he was arrested in Brazil in 1983, magistrate Falcone travelled out from Palermo, armed with a series of questions for Buscetta. Informed of his forthcoming interview with the Palermo magistrate, Buscetta opted to put on a bella figura, presenting himself to an astonished Falcone in a double-breasted white jacket, dark blue shirt with cravat and black trousers. He had long ago learned that a mafioso must always look in control of the situation.

Falcone presented Buscetta his list of questions. Don Masino read it carefully and then looked up: "Magistrate, how long have you got? It would take me all of today and well into tomorrow to begin answering this lot. . ."

Less than one year later, sensing that the circle was closing in on him and that it would be a close thing as to whether his former business associates back in Sicily or the long arm of the law got to him first, Buscetta cracked and attempted to commit suicide by swallowing strychnine. Within days of the failed suicide attempt, however, Brazil agreed to Italy's request for his extradition

Even at this late stage, he almost slipped through the noose. When Gianni De Gennaro, the senior Criminalpol officer sent to escort him back to Italy, arrived at Rio de Janeiro international airport on Friday July 13th, he found that no one - Italian consulate, Brazilian police or others - had bothered to book a ticket for Buscetta. De Gennaro had to argue hard with local airport authorities before he was finally allowed to leave with his precious cargo, having dipped into his own pocket to buy Don Masino's ticket home.

Three days later, Buscetta began his historic testimony. It went on for 45 days, prompting Falcone to order 3,600 checks on the evidence and resulting in the issue of 366 arrest warrants. Buscetta knew that his evidence would not sink the Mafia, but he knew likewise that it would strike a blow such as had never previously been struck, while also putting sworn enemies behind bars.

Buscetta had told Falcone much, but not all. When it came to naming those politicians who had colluded with Cosa Nostra, Buscetta warned Falcone: "You don't want to know, the time is premature."

In the meantime, though, Cosa Nostra inevitably fought back, first killing another three members of Buscetta's family, including two sons.

Later in court, in a dramatic confrontation with one of the mafiosi he had fingered, godfather Pippo Calo, Buscetta revealed something of his sense of personal vendetta. Infuriated by Calo's ploy of pretending not to know him, Buscetta thundered at him: "You who pretend not to know me, who brought up my own two boys, the same two that you had taken out. . ."

Cosa Nostra, of course, continued to fight back, striking a wounding blow at the Italian state when it blew up not only Giovanni Falcone in May 1992 but also his friend and mafia-investigating colleague, Paolo Borsellino, two months later. Those two killings prompted Buscetta to change tack.

The time was now ripe to name names, political names. In 1993, he named the biggest one of all - the seven-times prime minister of the post-war era.

In a celebrated exchange during Senator Andreotti's trial, defence lawyer Franco Coppi asked Buscetta if the evidence he had just given had been based on speculation or direct knowledge. Buscetta answered that his knowledge was based on the reality of life.

Life's reality might have been important to Buscetta. But as evidence in a court of law, it cut no ice. It thus came as little surprise when courts in both Perugia and Palermo rejected his evidence and acquitted Andreotti and new legislation insists that mafia turncoats give evidence based only on their direct knowledge.

The judgment disillusioned Buscetta: a disillusionment that was reflected in the title of his last books - The Mafia Has Won.