Samuel Flores Borrego

Samuel Flores Borrego (a.k.a. Metro 3; 6 August 1972 – 2 September 2011) was a Mexican drug lord and high-ranking lieutenant of the Gulf Cartel. He was a former state judicial policeman who protected the ex-leader of the Gulf cartel, Osiel Cárdenas Guillén. Upon his arrest, Flores Borrego became the right-hand man of Jorge Eduardo Costilla Sánchez, the former leader of the criminal organization.

Although born in Matamoros, Flores Borrego was closely linked to the city of Reynosa, Tamaulipas, where he served as the Gulf cartel's regional leader on and off for many years after serving as a policeman during the governorship of Tomás Yarrington (1998–2004) – the peak era of the Gulf cartel.

The Mexican authorities believe that Flores Borrego is responsible for the split of the Gulf cartel and Los Zetas, a cartel originally formed by deserters of the Mexican Army Special Forces hired in the late 1990s as the private army of the Gulf cartel. While operating in Reynosa in early 2010, Flores Borrego ordered the abduction and execution of a leader of Los Zetas. After the slaying, Los Zetas demanded Flores Borrego's death and threatened to go to war if the Gulf cartel did not hand over the assassin. Nonetheless, Flores Borrego ignored their demands and consequently broke the organization's alliance.

On 2 September 2011, Flores Borrego was found dead along with a local police officer on the outskirts of the border city of Reynosa, Tamaulipas. The Mexican authorities indicated that he had been killed by members within his own criminal group over disagreements and territorial disputes.