Mexican naval forces in the oil port of Tampico, Tamaulipas, on Sept. 13 arrested Jorge Eduardo Costilla Sánchez AKA "El Coss"—notorious leader of the Gulf Cartel—along with five cohorts, apparently without resistance. Authorities hailed it as a major blow against the cartel, coming just a week after the arrest of another Gulf kingpin, Mario Cárdenas Guillén AKA "El Gordo" (Fatso), captured by Mexican marines in Altamira, also in Tamaulipas—the brother of Osiel Cárdenas Guillen, who led the cartel until he was detained in 2003.

With the arrest of El Coss, Mexican authorities say they have now captured or killed 12 of the 24 figures identified by the Prosecutor General of the Republic (PGR) as controlling the country's narco trade. The others include Ezequiel Cárdenas Guillén AKA "Tony Tormenta" of the Gulf Cartel; Ignacio Coronel Villarreal, AKA "Nacho" and Vicente Zambada Niebla AKA "El Vicentillo" (also "El Mayito") of the Sinaloa Cartel; Arturo Beltrán Leyva AKA "El Barbas" and Edgar Valdez Villarreal AKA "La Barbie" of the Beltrán Leyva Organization (BLO); and Nazario Moreno González AKA "El Chayo" and José de Jesús Méndez Vargas AKA "El Chango" of La Familia Michoacana.

Among those who remain at large are Joaquín Guzmán AKA "El Chapo" of the Sinaloa Cartel; Heriberto Lazcano Lazcano AKA "El Lazca" and Miguel Angel Treviño Morales AKA "Z-40" of Los Zetas; Héctor Beltrán Leyva AKA "El H" of the BLO; and Servando Gómez Martínez AKA "La Tuta" of the Knights Templar. (NSS Oaxaca, Sept. 14; WSJ, Sept. 13; BBC News, Sept. 5; Houston Chronicle, Sept. 4)

Federal police also announced the capture in central México state Sept. 12 of Ramiro Pozos González, supposed chief of La Resistencia, an alliance formed by the Gulf, Familia and Milenio cartels to resist Los Zetas. (San Diego Union-Tribune, Sept. 12)

But there are fears that the arrests of top leaders could exacerbate power struggles within the cartels and actually escalate violence. On Sept. 14, officials found 16 bodies at two locations near the Texas border in Tamaulipas. Nine, including the body of a teen-age youth, were found in Nuevo Laredo—eight shot to death and one hanging from a bridge. Another seven bodies, most bound, were found in the town of San Fernando—near the place where a mass grave of 74 migrants was discovered in August 2010. (EFE, AP, Sept. 14)