An Eritrean man believed to be at the heart of the operation to smuggle migrants from Africa to Europe has been extradited to Italy, prosecutors say.
Mered Medhanie, known as The General, was held in Sudan in May and was flown to Rome on Tuesday.
Britain's National Crime Agency says he is thought to have arranged the transit of a boat that sank near the Italian island of Lampedusa in October 2013.
At least 359 migrants died when the boat, travelling from Libya, capsized.
Most were from Eritrea and Somalia.
Italian news agency Ansa said Mr Medhanie was accused of being "the leader and organiser of one of the largest criminal groups operating between central Africa and Libya".
Prosecutors accuse Mr Medhanie of running the network alongside an Ethiopian accomplice, who is still at large.
The two men are accused of buying up kidnapped migrants from other gangs and sending those migrants on barely seaworthy ships across the Mediterranean towards Europe.
The investigation is being led by investigators in the Sicilian city of Palermo. Mr Medhanie is expected to appear in court on Wednesday.
The UK's National Crime Agency said it had tracked him down to an address in Khartoum, where he was then arrested. The rare extradition from Sudan to Italy was completed in record time, reported Italy's La Repubblica (in Italian).