A woman who dares to cooperate with police in the fight against a dreaded Italian mob network is murdered, her body dumped in a barrel of acid in the countryside near Milan. Her 17-year-old daughter steps forward and testifies, helping to send six people to prison for life.

The lurid 2009 murder and the court verdict delivered in April gave a rare peek into Italy's secretive witness protection program, which marked its 20th anniversary this year and is considered Italy's single most important window into the secretive world of organized crime. Hundreds of mobsters have been given new identities in exchange for information that helped put longtime fugitive leaders behind bars, including the "boss of bosses" Salvatore Riina.

The use of insiders has combined with the seizure of mob assets to help Italy achieve a once unattainable goal: crippling the Sicilian Cosa Nostra.

"It has advanced immensely the fight against organized crime," said Felia Allum, a British academic who studies organized crime.

Italy's famed anti-Mafia prosecutors Giovanni Falcone and Paolo Borsellino had fought in the 1980s to establish the two anti-mob weapons, arguing that criminals needed some incentive to step forward and turn state's evidence. They were killed by mob bombs within two months of one another in 1992, but not before they'd laid the foundations for a crime-fighting system that has largely tamed, if not defeated, the Mafia.

Living under state protection does take exact a heavy toll on witnesses.

A major problem is that most mobsters in the program are from Italy's underdeveloped south, and they are generally exiled to what they see as a hostile environment in the prosperous north, because it's easier to hide them there. There have been suicides. Some return to crime when their collaboration with the state comes to an end.

"They are given a new identity and a lump sum of money to start their new life but they are not helped as much as they should be to reintegrate back into society," said Allum.

The dead woman in the 2009 murder, 36-year-old Lea Garofalo, had left the government program "feeling uneasy" about her protection, her lawyer Vincenza Rando said, adding that she was subjected to unwanted sexual advances from her police guards. "She didn't feel well protected and risked it on her own."

Garofalo's daughter Denise felt that her mother's decision had cost her life, so she decided to put her trust in the program. She was the key witness in the trial and now lives with a new identity in an undisclosed location. The contrasting fates of mother and daughter underscore how critical it is for witnesses in mob cases to obtain new identities. Without one, experts say, turncoats like Lea Garofalo become sitting ducks for inevitable revenge killings.

Denise Garofalo is one of nearly 4,700 people in the program -- about 1,000 so-called "collaborators" who have turned state's evidence and the rest family members, according to a document obtained by The Associated Press on figures up to 2010. It is believed to be the second largest program after that of the United States. Most have been witnesses in cases against the Sicilian Mafia, the Neapolitan Camorra and the Calabrian 'ndrangheta --the crime syndicate in the Garofalo case.

Prosecutors say that no one who has followed the protection rules has been harmed. Those who stray do so at their own peril, like the son of a Camorra boss who returned to his hometown and was slain.

Changing immigration patterns and the spread of international terrorism have led authorities to open the program to eastern Europeans, North Africans and several other nationalities, according to the Interior Ministry report to parliament.

Lazhar Ben Mohamed Tlil, a Tunisian who became an Islamic militant and was trained in Afghanistan to kill Americans, entered the witness protection program after providing information to Italian investigators about several detainees at Guantanamo, his court-appointed lawyer, Davide Boschi, told The Associated Press.

The lawyer has said that Tlil, considered an important witness by both Italians and Americans, would not talk to prosecutors without firm guarantees of a new identity, documents, a job, medical coverage and a visit to his parents in Tunisia.

An Interior Ministry report to parliament acknowledged criticism of the way the program works due to a "large, unexpected influx of people" into the program recent years. Witness protection costs some €100 million (more than $100 million) a year. It often fails to help former criminals return to normal life. And foreigners in the program face tough bureaucratic roadblocks to creating decent lives in Italy.

Still, criminal experts give the program high marks despite the headaches it faces in determining who may be lying, creating new identities and trying to hide the turncoats in Italy, where authorities have fewer options than in the much larger United States.

"By demonstrating that its institutions are standing as one in facing the Mafia, Italy is setting an example for the world against organized crime," Interpol Secretary-General Ronald K. Noble told a convention on organized crime in Sicily over the summer.

Until Italy established the program in the early 90s, the most famous witness, Tommasso Buscetta, needed to be sheltered abroad. He helped convict some 350 mobsters in the 1980s before being given a new identity in the United States in the American witness protection program.

While the release of criminals with blood on their hands has been contentious, Alfonso Sabella, a former Palermo prosecutor defended Italy's witness protection program in an interview with the Turin newspaper La Stampa.

It was, he said, a "necessary choice — when it was clear that the Mafia couldn't be brought to its knees through traditional means."


AP correspondent Colleen Barry contributed from Milan.