The rival gangs began a war of their own, one that rocketed the homicide rate to between 12 and 18 deaths per day in a country of 6 million people, and fundamentally altered the social fabric.
"We are not a little group of 100 or 200 people," Mojica says. "We are thousands upon thousands upon thousands.... We are a segment of society," he says, referring to El Salvador's some 64,000 gang members, according to Security Ministry statistics. "They can lock up some of us for some of the time, but they can't get rid of us."
Over the past two decades, a series of right-wing governments fought the gangs head-on. The left-leaning administration of President Mauricio Funes, who took office in 2009, also initially took a hard line, prompted in part by public outrage after members of the 18th Street gang set fire to a bus in June 2010, killing 17 people.
Mr. Funes subsequently deployed the military to take control of the country's prisons and proposed the 2010 law that made it illegal to be a gang member. El Salvador's run-down prisons – which lack the very basics including electricity and potable water – today hold some 26,000 people, though they were built for a capacity of 8,000. In Cojutepeque, more than 1,000 men, most of them abundantly tattooed members of the 18th Street gang, crowd into quarters constructed for 250.
Thirty percent of prisoners have not been formally sentenced, which illustrates problems endemic in El Salvador's justice system. Yet combating the gangs head-on, and jailing leaders, did little to stop homicides, which stood at 69 per 100,000 in 2011, according to the United Nations. The UN ranked El Salvador as one of the world's most violent nations not at war.