The rupture from Los Zetas left Jorge Eduardo Costilla Sánchez and Antonio Cárdenas Guillén in full control of the Gulf Cartel. However, Ezekiel died in a shooting with the Mexican Marines in Matamoros, Tamaulipas in 2010, and Costilla Sanchez became the sole head of the cartel until his arrest in September 2012. Mario Cárdenas Guillén, brother of both Osiel and Antonio, became one of the top lieutenants in the organization after his release from prison in 2007. In addition, within the Gulf Cartel there is believed to be two groups—the Rojos and the Metros. The modus operandi ("mode of operation") of the Gulf Cartel changes whenever the United States attempts to strengthen their domestic policy in reinforcing the borders. When drug trafficking tightens, they usually invest in more sophisticated methods to smuggle drugs, recruit new members, corrupt more officials, seek new ways to remove obstacles that impede the immediate success of the organization, along with many others. Below is the basic structure of the cartel: