Development: On 5 August Chuck Rosenberg, the acting head of the US Drug Enforcement Administration (DEA), said that the escaped leader of the Sinaloa drug trafficking organisation (DTO), Joaquín ‘El Chapo’ Guzmán, was probably still in Mexico, and that the agency was stepping up its attempts to bring him to justice. Significance: A key issue in the attempt to control Mexican DTOs is the quality of the collaboration between Mexican and US law enforcement agencies. Rosenberg’s comments at a press briefing show that despite US reservations about drug gang infiltration of the Mexican police, the two governments maintain a degree…