Former communist militant Cesare Battisti was handed over to Italian authorities by Bolivian officials in Santa Cruz this evening and put on a plane headed for Rome.
Battisti, an Italian man convicted of four murders in absentia, had been on the run for almost four decades before he was captured by police in Santa Cruz yesterday following an Interpol operation.
"The plane carrying Cesare Battisti has just taken off headed for Italy. I am proud and moved!" Italian Interior Minister Matteo Salvini tweeted.
Italy had repeatedly sought the extradition of Battisti, 64, who lived in Brazil for years under the protection of former leftist president Luiz Inacio Lula da Silva, who is now in prison for corruption.
Battisti escaped from an Italian prison after being convicted in 1979 of belonging to an outlawed leftist group, the Armed Proletarians for Communism.
He was subsequently convicted in absentia of having killed two Italian policemen, taking part in the murder of a butcher, and helping plan the killing of a jeweller who died in a shootout which left his 14-year-old son in a wheelchair.
Battisti admitted to being part of the group but denied responsibility for any deaths.
He reinvented himself as an author writing a string of noir novels and in 2004 skipped bail in France, where he had taken refuge.
He went to live clandestinely in Brazil until he was arrested in 2007 in Rio de Janeiro.
After years in custody, then-president Lula issued a decree - later upheld by Brazil's Supreme Court - in 2010 refusing Battisti's extradition to Italy, and he was freed, angering Italy.
Battisti, who has a five-year-old Brazilian son, last year said he faced "torture" and death if he were ever to be sent back to Italy.
"Italian terrorist Cesare Battisti was detained in Bolivia and will be soon brought to Brazil, from where he will probably be sent to Italy to serve a life sentence," tweeted Filipe G Martins, a senior aide on international affairs to Brazilian President Jair Bolsonaro.
During Brazil's recent presidential campaign Mr Bolsonaro - who took office on 1 January - vowed that if elected he would "immediately" extradite Battisti to Italy.
In mid-December Brazil's outgoing president, Michel Temer, signed an extradition order for Battisti after a judge ordered his arrest. By then the Italian ex-militant had disappeared.
Battisti was arrested late last night in the Bolivian city of Santa Cruz de la Sierra, Brazilian police sources told Brazilian media. Italian interior ministry sources confirmed the arrest.
"Battisti was arrested in the street, unarmed and he didn't resist, responded to police in Portuguese and showed a Brazilian document confirming his identity," an Italian interior ministry source said.
"Now Italy is waiting for him."
Italian state police said the arrest had been carried out by a joint team of Italian and Bolivian officers with the help of Italy's counter-terrorism section.
According to the Italian government sources, Battisti was spotted "with certainty" in Santa Cruz last week and an operation was prepared with local authorities.