Beto the Gypsy is accused of smuggling tones of cocaine into the US and Europe
An alleged Colombian drugs lord, Edgar Guillermo Vallejo-Guarin, has been arrested in Spain.
Mr Vallejo-Guarin, known as Beto the Gypsy, is wanted for drugs-trafficking, money-laundering and murder.
Spanish police say he was using a false identity when they arrested him at a luxury hotel in the capital, Madrid.
The US authorities say he is one of Latin America's top drugs traffickers and had offered a $5m reward for information leading to his arrest.
The BBC's Danny Wood, in Madrid, says Beto the Gypsy, 47, is suspected of transporting tonnes of drugs into the US and Europe.
The US Drugs Enforcement Administration says he was one of the main sources of Colombian cocaine smuggled into America in the 1990s.
He has been a fugitive since 2001, when he was indicted by a court in Florida.
Police said he had been constantly on the move to avoid arrest, staying in hotels across Europe, and was carrying false documents when he was arrested.
Spain is one of the main entry points to Europe for cocaine smuggled from South America.