El Salvador's president Funes has told Al Jazeera he is increasingly concerned about the recruitment of some of his country's most feared gangs or Maras. In particular, the MS 13, Mara Salvatrucha, who are being co-opted by Mexico's brutal Zetas cartel to work for them. In the country's poorest neighbourhoods young people are recruited as the foot soldiers of drug cartels in charge of extortion, kidnapping and killing. Al Jazeera's Lucia Newman reports from El Salvador's capital.