Born in Cambados, Oubiña began working in his parents' grocery store at the age of 10, and by 15 was distributing products by van to street hawkers.

He began his criminal career at the age of 17, at first participating in diesel smuggling with his uncle, and a few months later founding his own black market tobacco company.

Police searched a number of his companies and his personal residence, the Pazo Baión, on 6 July 1989, where sophisticated telecommunications equipment and a rifle were discovered; less than a year later, on 23 April 1990, he was acquitted on charges of smuggling and illegal possession of firearms, but sentenced to four months for resisting the authorities.

[11] Just a few days after the culmination of Operation Sunset in October 1999, Oubiña was for the first time sentenced for drug trafficking by the Audiencia Nacional, the Spanish high court.

[12] Oubiña was detained along with his stepson David Pérez Lago in Greece in 2000, pursuant to an international arrest warrant issued against him after escaping custody during Operation Sunset.