Alan Gomez

USA TODAY

MIAMI — Despite improved security among its neighbors, El Salvador faced an explosion of homicides in 2015, likely making it the murder capital of the world.

The surge in violence explains why thousands of Salvadorans and other Central Americans have fled to the United States and why immigration officials are stepping up efforts to send them back home.

Government data show 6,657 people were murdered in the small country last year, a 70% increase from 2014. The homicide rate of 104 people per 100,000 is the highest for any country in nearly 20 years, according to data from the World Bank.

"Keep in mind, you're talking about the national average," Adriana Beltrán of the Washington Office on Latin America said about El Salvador's homicide rate. "If you start looking at where the pockets of violence are, it's shocking."

El Salvador's violence has worsened, even as other countries in the region have shown improvements.

All countries south of the U.S. border face the same problem: cartels and gangs fighting to control smuggling of drugs and people to the United States and infiltrating government institutions to help them. Each has used different methods to stem the problem.

In Guatemala, the situation improved, in part, because of nearly a decade of work by the International Commission Against Impunity in Guatemala, a group created by the United Nations in 2006 to support prosecutors and law enforcement. The group targeted corrupt government officials who allowed criminal organizations to thrive. Its efforts culminated last year with the arrests of President Otto Perez Molina, his vice president and top aides.

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While that tactic worked for Guatemala, it's unlikely to be a blueprint for El Salvador, said Jose Miguel Cruz, who has studied violence in Central America for three decades and now serves as director of research at the Latin American and Caribbean Center at Florida International University in Miami.

Cruz said the U.N. commission was successful in Guatemala because its government was helpless, and citizens protested loudly. El Salvador's leaders have rebuffed similar outcries, fearing a loss of power and exposure to prosecution.

"That's the flip side of having stronger institutions — they're still corrupted," Cruz said. "I think they realized that at some point, (foreign intervention) would touch their own interests."

In Honduras, the drop in reported homicides — from 5,891 in 2014 to 5,039 last year — may partly reflect informal agreements between cartels and the government, said Jeannette Aguilar, director of the Institute of Public Opinion at the Central American University in El Salvador.

She said similar agreements helped quell violence in Guatemala and El Salvador and appear to be working in Honduras. As the truce in El Salvador broke down in recent years, the same could happen in Honduras, Aguilar said.

It's possible the apparent reductions in violence in Central America are not true, Aguilar said. Cartels understand the backlash if too many murders take place in communities they control, so they've learned to dispose of bodies so they're not counted in official records, she explained.

"Because of the evolution of dismembering bodies, decomposing them, incinerating them, it's difficult to know if homicides have really fallen," she said.

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Some help may be on the way for the region. Congress last month approved $750 million to help El Salvador, Guatemala and Honduras tackle organized crime.

Cruz said that could go a long way toward reducing the violence. "I would expect some changes, not only because of the new (homicide) data and the international outcry about it," Cruz said. "But also because of the $750 million. I think the U.S. has the intention to demand some results."