Six in 10 Mexican prisons 'self governed' by gangs Earlier this month, more than 130 inmates escaped from a prison near the U.S. border in Piedras Negras, Coahuila, one of numerous mass breakouts tied to organized crime in the past few years. "A good number of (Mexico's) prisons feature similar conditions to those at Piedras Negras," Mr Aguirre said. Overcrowding of the country's prisons and jails is another problem facing the national penal system. As of July, Mexico's overall prison population stood at 48,872 inmates, or 25 percent above the system's official capacity. Mexico also faces a shortage of prison guards relative to international norms, Aguirre said. The commission's findings are a reminder of the challenges that await Enrique Pena Nieto, Mexico's incoming president, who has pledged to reduce crime in the country after six years of increased gang-related violence under President Felipe Calderon.