The drug traffickers had no idea there was a spy among them, nor could they ever imagine that the infiltrator was the man who built, repaired, and operated superfast motorboats for some of the most ruthless criminal organisations on the planet.

For four years, Gianfranco Franciosi, or Giannino as everyone calls him, was trusted by everyone, from Italian mafiosos to Colombian and Spanish drug barons.

He was able to transform an old dinghy into the equivalent of a seaborne Ferrari, the perfect smuggling vessel for tonnes of cocaine. But he would also plant listening devices.

On 26 February 2009, the intelligence he gathered led to the arrest of numerous drug traffickers and the seizure of nine tonnes of cocaine. That day Giannino’s work as a police informant was over, and his nightmare began.

Known as Italy’s Donnie Brasco after the alias of the FBI agent who infiltrated the mafia in New York in late 70s, early 80s, Giannino now lives in a caravan in northern Italy.

Having been used to infiltrate the drug cartels, or narcos, by the Italian state, he now faces debts and death threats from the those who razed his €1.5m a year ship-building business to the ground in 2015. He accuses the authorities of abandoning him.

“I betrayed the narcos, but I realised that the Italian state betrayed me,” he says.

Giannino is one of many former police informants and state witnesses used in antimafia operations who then become victims of a broken system that is unable to provide safety and support, primarily because of budget constraints.

Many former business people who have denounced the mafia over il pizzo (protection money) have ended up bankrupt. Others have left the country, and a few, weighed down with debt have suffered depression, with some taking their own lives. Rocco Greco, a businessman from Gela in Sicily, killed himself this month after his company was accidentally placed by the interior minister on a list of businesses suspected of having mafia ties, barring his firm from bidding for public contracts.

Giannino has contemplated suicide. “Three times to be exact,” he says. “It happens when you’ve risked it all for the state and you realise that to them your life is rubbish.”

Marcello Bruzzese, the brother of a former mafioso, was killed returning home in Pesaro. Photograph: Il Resto del Carlino (Bologna)/Fotoprint

Information gathered from police informants and state witnesses is one of the most effective instruments against mafia clans, but the price they pay can be high. The list of those murdered is long and continues to grow. The most recent was on Christmas Day last year, when the brother of a mafia member turned informant was shot by two hooded men in what police believe was an attack ordered by the ’Ndrangheta, one of Italy’s most powerful mafia groups.

Tommaso Buscetta, whose revelations in the 1980s dealt a death blow to the more famous Sicilian mafia, the Cosa Nostra, may have paid the highest price. Between 1982 and 1984, his brother, son-in-law, brother-in-law and four grandchildren were killed, and two sons disappeared.

In Italy, the problem of judicial recognition and witness protection has become serious and widespread. According to official data from the interior ministry, about 6,200 people are under witness protection in Italy, including family members.

Generally, state witnesses are paid a monthly stipend of €1,000 to €1,500 each, plus an additional €500 a month for each family member.

But the state no longer has the necessary economic resources to protect collaborators.

Matteo Salvini, the interior minister, has announced a review on police protection spending. Photograph: Giuseppe Lami/EPA

Last week,the country’s far-right deputy prime minister and interior minister, Matteo Salvini, announced his ministry would review spending on police protection for those under threat from the mafia, saying: “Some people have been under police escort for too long.”

There have been growing calls for better and longer protection for state witnesses or police informers.

Ignazio Cutrò, a Sicilian businessman and president of the National Association of State Witnesses, received numerous threats, including torched cars and packages containing bullets, after agreeing to testify against suspected extortionists and entering witness protection.

Despite the intimidation, last year protection for him and his family was revoked. “Italy is pushing people to rebel against the mafia, but when the state gets what it wants, it abandons them. We are a bunch of dead men walking,” he says.

Other have had to flee Italy. Last year, Maria Vallonearanci, who reported her husband, a boss in the ’Ndrangheta, to the authorities, moved to Germany because mafia bosses were able to find her “even in state-designated safe havens”.

For the same reason Fabrizio Demitri, a former informant, and his wife, a cousin of a boss from Apulia, fled with their children to Canada, requesting asylum after local clans had poisoned two of their dogs and men tied to the mafia had located them while in hiding.

Giannino had sought shelter in France, but to no avail. Some EU countries refuse to accept citizens from other member states on asylum grounds because they consider the home countries capable of providing sufficient assistance. In other cases the problem is solely bureaucratic.

The hiring of a police officer or civilian for an undercover assignment in a mafia clan goes through intelligence units. For securities reasons, other police agencies are often not officially informed about the existence of an informant. This can later complicate requests for state protection or economic assistance because the informer’s name does not appear in official documents, or his or her role has never been communicated outside the intelligence service.

In July 2007, Giannino was arrested by French police while working undercover. He hoped that sooner or later it would be acknowledged that he was an informant, but the Italian police failed to inform their French colleagues of his role. He spent seven months in prison before Rome finally got him out.

Last Monday, the Italian movie star Beppe Fiorello announced that filming of a TV series based on Giannino’s story will begin in May.

“Very few [informants] manage to start over,” says Piera Aiello, an MP who revealed she was a state witness on being elected last year. “The majority of police informers and state witnesses ends up bankrupt or suffering from depression. And what’s worse is that there is no psychological support for these men and women who are forced to live like prisoners, while mobsters are still at large.”

Aiello is now a member of the Italian parliamentary antimafia commission.

A law passed last year obliges the state to provide former informants alternative employment. All Giannino was offered was a job as an undertaker in a cemetery for little more than €1,000 a month. To make ends meet, he sold a Rolex given to him by the head of a Spanish drug cartel for €1,500.

“It wasn’t a real gift,” says Giannino. “It was more like a contract. A way to tell me that my time belonged to the narcos. My contract as an undercover cop with the state was in the form of my signature on dozens of enormous files. That, too, was a way to tell me that my time belonged to them. What wasn’t written in the documents was that that state would take my life, too.”