Question: Osiel Cárdenas Guillén was the leader of the syndicate that was part of what country?
Sentence (from "Osiel Cárdenas Guillén"): Osiel Cárdenas Guillén (born May 18, 1967) is a former Mexican drug lord and the former leader of the Gulf Cartel (Spanish: "Cártel del Golfo" ) and Los Zetas.
Relevant evidence: Yes