Cesare Battisti had been living in Brazil after fleeing Italy in 1981 while awaiting trial on four counts of murder. He denies killing anyone but was convicted in 1990 of four murders.
Former communist militant Cesare Battisti was handed over to Italian authorities and put on an airplane heading for Rome on Sunday after an international police squad tracked him down and arrested him in Bolivia, where he had been on the run.
The airplane left the Santa Cruz international airport in Bolivia shortly before 5:00 pm (2100 GMT) after local authorities handed over the 64-year-old fugitive to their Italian counterparts.
"The airplane with Battisti has just left for Italy: I'm proud and delighted," Italy's Interior Minister Matteo Salvini tweeted.
Battisti was arrested in Santa Cruz late on Saturday in an operation carried out by a joint team of Italian and Bolivian officers with the help of Italy's counterterrorism section, Italian state police said.
He had spent almost four decades on the run.
Jailed in 1979 for belonging to the outlawed Armed Proletarians for Communism group, Battisti had been on the run since escaping prison in 1981 and was convicted in absentia of four murders in Italy in the 1970s.
Italy had repeatedly sought the extradition of Battisti, who lived in Brazil for years under the protection of former leftist president Luiz Inacio Lula da Silva (2003-2010), himself now in prison for corruption.
When he was arrested, Battisti, 64, gave up without a struggle after reportedly being caught disguised in a false beard and moustache, Italian interior ministry sources said.
"I just spoke to Brazil President Jair Bolsonaro on the telephone. I wanted to thank him on behalf of the whole Italian government for the effective collaboration that led to Battisti's capture," Italian Prime Minister Giuseppe Conte posted on Facebook.
During Brazil's recent presidential campaign far-right Bolsonaro – who took office on January 1 – vowed that if elected he would "immediately" extradite Battisti to Italy.
In mid-December Brazil's outgoing president, Michel Temer, signed an extradition decree for Battisti after a judge ordered his arrest. By then the Italian ex-militant had disappeared and gone on the run.
"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."
Italy's envoy to Brazil fired off a triumphant tweet upon hearing the news. "Battisti has been arrested! Democracy is stronger than terrorism!" Ambassador Antonio Bernardini wrote.
According to Italian government sources, Battisti was spotted "with certainty" in Santa Cruz last week and an operation was prepared with local authorities.
An Interpol team had targeted their search in Santa Cruz before Christmas, closing in on the Italian fugitive in a few of the city's neighbourhoods, the paper said.
Battisti had filed for asylum without receiving any response from authorities, Bolivia's ombudsman said in an article published in the local El Deber de Santa Cruz newspaper.
He had been hoping to find favour with Bolivia's left-wing President Evo Morales after saying in his asylum request that he'd been forced to quit Brazil due to "the ominous coincidence" that Italy and Brazil were both now run by "far-right" governments.
Prison fugitive, author
Salvini thanked the Italian and foreign police who captured "a delinquent who did not deserve the comfortable life on the beach, and who should spend the rest of his days in prison."
Bolsonaro's son, Brazilian lawmaker Eduardo Bolsonaro, tweeted in Italian with a picture of Battisti: "Brazil is no longer the land of bandits. Matteo Salvini, the 'little gift' is on its way."
After escaping prison, Battisti was convicted in absentia of having killed two Italian policemen, taking part in the murder of a butcher and helping plan the slaying of a jeweller who died in a shootout that 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.
In 2004, he 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 Rome.
Battisti, who has a five-year-old Brazilian son, last year told AFP he faced "torture" and death if he were ever to be sent back to Italy.