Trial over brutal killings sheds light on MS-13 and power of US street gangs

Complex social and political elements swirl round gang - with roots in El Salvador - accused of hacking four US teens to death

The mythology of the street gang is rooted in American popular culture, from West Side Story to The Warriors to Training Day.

But a recent trial in the seemingly endless suburban landscape of Long Island, New York, has thrown a spotlight on the harsh reality of gang activity, and the circumstances in which it flourishes. In particular, one of the most brutal organizations at work in the US: Mara Salvatrucha, or MS-13.