A man accused of being a leading member of the Cali drugs cartel has given himself up in the Colombian city of Bucaramanga, police say.
Colombia produces 70% of the world's cocaine
Daniel Serrano Gomez allegedly served as the accountant of the drug ring which dominated the world's cocaine trade in the 1990s.
He is thought to be the third highest-ranking Cali cartel member in custody.
The two brothers who founded the group, Miguel and Gilberto Rodriguez Orejuela, were imprisoned in 1995.
The Rodriguez brothers obtained the monopoly of the multi-billion dollar cocaine industry after rival drug lord Pablo Escobar was killed by police in 1993.
US authorities had requested the extradition of all three, plus eight other associates, on 18 December.
The extradition order alleges that the Rodriguez brothers have continued to run their empire from their prison cells in Colombia, where they have been confined since 1995.
They are charged with smuggling 55 tonnes of cocaine, laundering about $2bn and silencing those who might testify against them, either through bribery or by murder.
Gilberto Rodriguez Orejuela was re-arrested in March this year
Drug smugglers face tougher jail sentences in the US than in Colombia.
If the request goes ahead, the brothers would become the highest-profile drug lords to be sent to the US to face justice since Colombia lifted a ban on extradition in 1997.
But there are still several hurdles to cross.
The request must be authorised by President Alvaro Uribe and the supreme court.
As extraditions to the US are a sensitive issue in Colombia, correspondents say it is unclear how the president will act.