El Salvador's MS-13 gang: Life on the inside
20 November 2012 Last updated at 17:54 GMT
More than 2,500 members of the Mara Salvatrucha street gang, or MS-13, are serving time in El Salvador's Ciudad Barrios prison.
Jose Luis Mendoza, a founding member of the gang, which originated in west Los Angeles in the early 1980s, showed the BBC around the prison - a facility built to house just 800 inmates.
Deported three times from the United States, Jose Luis Mendoza is now serving 52 years for murder in the Salvadoran prison.
Video journalist Dave O'Neill
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