TULTITLAN, Mexico -- Deported from the United States after years working construction in New Jersey, Hector Augusto Lopez decided to rebuild his life in his hometown in eastern Honduras.

He found a steady job in a shoe store in Catacamas. Then, in March, he watched horrified as robbers shot three customers to death before his eyes. Soon after, he decided to make the hard and dangerous journey north again.

"In Honduras there is a lot of violence, a lot of robberies and a lot of poverty," Lopez, 28, said as he waited to jump a cargo train just outside Mexico City on a recent afternoon. "There is no future there."

Half a block away, dozens more U.S.-bound Central American migrants waited outside an overflowing one-story, crammed shelter, napping on pieces of cardboard, wrapping themselves in garbage bags against the cold and trading stories about their journeys north.

While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. Other factors, experts say, are an easing in migration enforcement by Mexican authorities, and a false perception that Mexican criminal gangs are not preying on migrants as much as they had been.

Central American migration remains small compared to the numbers of Mexicans still headed north, but their steeply rising numbers speak starkly to the violence and poverty at home. The perils of the journey have pushed smuggling fees as high as $7,000, as much as double the earlier rates, for a trip that takes weeks, or even months for those delayed by robberies, health problems or difficulties finding transportation.

Honduras, with a population of 8.3 million, had the world's highest homicide rate in 2010, with 6,200 killings, or 82.1 murders per 100,000 inhabitants. That's up from 57 murders per 100,000 inhabitants in 2008. Neighboring El Salvador had 66 homicides per 100,000 in 2010. The U.S., by comparison, saw about 5 homicides per 100,000 people.

"The reality is that a lot of Mexicans have sort of given up looking for work in the U.S. and have started to return home but for Central Americans the conditions may be even more desperate that the ones we're seeing in Mexico," said David Shirk, director of the Trans-Border Institute at the University of San Diego.

About 56,637 non-Mexican migrants, most of them Central Americans, were detained by the U.S. Border Patrol along the border with Mexico between October and May. That's more than double the 27,561 detained in the same period a year ago. Meanwhile, the number of Mexican migrants caught at the U.S. southern border decreased 7 percent this fiscal year, to 188,467.

In fact, the illegal migration of Mexicans to the United States now stands at its lowest level in decades, according to a study released in April by the Washington-based think tank the Pew Hispanic Center. The study found that over the last five years more Mexicans have left the United States than entered it.

Much of the drop is attributed to a weak U.S. economy, which has principally shrunk the number of construction jobs attractive to Mexican workers. Increased deportations, heightened U.S. patrols and violence along the border, as well as Mexico's declining birth rate, also have played a role.

When it comes to Central Americans, the picture is starkly different.

U.S. apprehensions of undocumented migrants, including Central Americans, began declining in 2007, when the flow of undocumented migrants began slowing, but experts say that has reversed as violence rises in Central America, partly fueled by Mexican drug cartels moving into the area. Although Mexican authorities have pulled back on some immigration enforcement, they also have been apprehending more undocumented Central American immigrants before they get to the U.S. border, with 29,619 arrested between January and April, a 42 percent increase from 2011, according to the country's National Immigration Institute.

Officials at the U.S. Customs and Border Protection did not respond to repeated requests for comment.

"We hadn't seen this amount of people in at least four years," said Sister Leticia Gutierrez, director of a Mexican Catholic bishops ministry that coordinates 54 migrant shelters across Mexico where Central Americans make up almost all the client population. "People keep coming, and coming, and coming, so much so that we're scrambling to help those who arrive to the shelters because we run out of the few things we have to give them after the first trains of the day arrive."

Most hop on freight trains heading to the border with Texas, which is the closest U.S. spot from Mexico's southern border, and the most dangerous route.

As they head north on the sun-scorched trek, the migrants often pay off thieves, immigration officials, police and railroad employees. They also have to cross territory controlled by the Zetas gang, which has increasingly targeted migrants, kidnapping them for ransom or holding them for forced labor.

The Zetas massacred 72 migrants in the summer of 2010 in the northern state of Tamaulipas, across the border from Texas. Nine months later authorities in Tamaulipas unearthed 193 bodies from clandestine graves after security forces said they were led to the site by Zeta members who confessed to kidnapping and killing bus passengers, many of them migrants.

With pressure mounting that Mexico ensure migrant safety, the federal government in 2010 ordered immigration agents to stop all night raids and cut back on day raids of northbound cargo trains, the main mode of transportation for Central Americans. Detentions at migrant shelters also ended, said Mexico's Immigration Commissioner Salvador Beltran del Rio.

"This (was put in place) in response to requests from these organizations and the governments of these countries, but it also reflects the fact that we think it is also appropriate for the safety of immigration agents," Beltran del Rio said.

Last year, rights activists reported that the Zetas were at times kidnapping up to 50 migrants in one swoop, often in complicity with immigration officials.

Activists say the lack of mass abductions has persuaded some migrants that things are better in Mexico. Nonetheless they warn that migrants are still putting themselves at risk.

"Now they are kidnapping two or three migrants at a time and in remote areas of central Mexico, where there aren't as many migrant shelters and where the kidnappings get no media attention," said Ruben Figueroa, a migrant rights activist in the southern state of Tabasco.

In the latest massacre attributed to the Zetas, 49 decapitated bodies with their feet and hands cut off were dumped in May on a Nuevo Leon state road about 75 miles south of the Texas border. Authorities have not ruled out the possibility that the victims were also U.S.-bound migrants. Without recent reports of mass kidnappings, the victims may have been some of those kidnapped in small groups over recent months.

The dangers aren't due only to criminals. Hundreds of Central American migrants were stranded in southern Mexico in late June after a rail bridge collapsed blocking the passage of cargo trains used by travelers heading to the United States.

Some of the migrants are continuing their journey north on foot or hitching rides in trailer trucks and other vehicles, migrants rights activists and Mexican authorities said.

"Those who can't get a ride have to walk and walk and walk," Sister Gutierrez said. More than 200 of the stranded migrants have asked federal immigration authorities in the state of Veracruz to deport them, said Rafael Pretelin, a federal immigration official in the Gulf Coast state.

Manuel de Jesus Chavez, a 16-year-old from Copan, Honduras, was heading to Texas to join his older brother who crossed illegally last year and has been working at a cattle ranch near Houston.

"He tells me they don't pay as well as he thought but that there is work," Chavez said on a recent afternoon while waiting in a food line at the Saint Juan Diego shelter in Tultitlan.

Built for 60 people, the single-room shelter crowded with double-decker bunks had been receiving up to 300 migrants a day, said the Rev. Christian Rojas.

Rojas said workers had to arrange makeshift beds on the concrete floor and in the patio to get as many people inside as possible. Migrants left outside were targeted by smugglers and passing drug traffickers, he said.

The migrants have also been the target of animosity from people in Lecheria, as the neighborhood surrounding the migrant center is known. It temporarily closed this week after people upset with clusters of men and women lingering outside their homes blocked the streets to stop volunteers from delivering food.

Gutierrez said the shelter closed because the government couldn't guarantee the volunteers or the migrants' safety.

"The migrants went from being in a situation of vulnerability, to a very grave situation," she added.

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  • In this May 17, 2012 photo, migrants, mostly from Honduras, rest on railroad tracks as they wait for a train headed north, in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 12, 2012 photo, Central American migrants walk on a railway in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • Edwin Omar Fuentes, a migrant from Honduras, stands by the train tracks as he recovers from an injury he got the night before in an altercation over a piece of clothing, in Coatzacoalcos, Mexico, Wednesday, July 11, 2012. Local officials estimate one thousand immigrants are stranded in this town after a rail bridge collapsed blocking the passage of cargo trains used by the travelers heading to the United States. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Miguel Juarez)

  • In this May 17, 2012 photo, Maria Campos, waits for customers to sell them food from her car, parked near the train tracks where migrants, mostly from Honduras, wait for trains going north, in Lecheria on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 17, 2012 photo, migrants, mostly from Honduras, watch a southbound train pass by as they wait for one going north, in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 17, 2012 photo, migrants, mostly from Honduras, wait for a train going north in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 17, 2012 photo, Krambilm Kennedy, a migrant from Nicaragua, leans up against a wall and eats, on the opposite side of the street of a shelter for migrants, where a sign hangs from a wrought iron fence that reads in Spanish: "The neighbors of Lecheria demand the closure of the migrant house," in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 17, 2012 photo, migrants sit outside the mayor's residence after protesting violence against migrants in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this May 12, 2012 photo, Central American migrants rest at a migrant shelter while waiting for a northern bound train in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • In this May 12, 2012 photo, a Central American migrant, who lost a leg when he fell from a train, walks on crutches along the tracks while waiting for a train to continue his journey to the US-Mexico border, in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • In this May 12, 2012 photo, Manuel de Jesus Chavez, 16, a migrant from El Salvador, waits for a north bound train to continue his journey to the US-Mexico border, at a shelter in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • In this May 12, 2012 photo, Central American migrants watch television while waiting for a north bound train to continue their journey to the US-Mexico border, at a migrant shelter in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • In this May 12, 2012 photo, Eric Acosta, a migrant from Honduras, recovers from a fall he suffered while trying to climb a north bound train, at a migrant shelter in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Marco Ugarte)

  • In this May 17, 2012 photo, Mexican street artist Ezer Alvarado performs in front of migrants waiting for a north bound train, in Lecheria, on the outskirts of Mexico City. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Alexandre Meneghini)

  • In this photo taken Tuesday, July 10, 2012, hundreds of Central American migrants make their way by foot as they leave the city of Coatzacoalcos, Mexico. Local officials estimate one thousand immigrants are stranded in this town after a rail bridge collapsed blocking the passage of cargo trains used by the travelers heading to the United States. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Felix Marquez)

  • Central American migrants line up for bread and coffee during their wait for a northern bound train, in Coatzacoalcos, Mexico, Wednesday, July 11, 2012. Local officials estimate one thousand immigrants are stranded in this town after a rail bridge collapsed blocking the passage of cargo trains used by the travelers heading to the United States. While the number of Mexicans heading to the U.S. has dropped dramatically, a surge of Central American migrants is making the 1,000-mile northbound journey this year, fueled in large part by the rising violence brought by the spread of Mexican drug cartels. (AP Photo/Miguel Juarez)

  • Marlon Roberto Cortes poses for a portrait in Tegucigalpa, Honduras, Sunday, June 18, 2012. Cortes was working in a suburban Boston supermarket when he was summoned to the back office and deported to his country last March, missing by three months President Barack Obama's decision last week to allow hundreds of thousands of illegal immigrants no older than 30 with high school degrees and no criminal history a chance to stay and work in the country.(AP Photo/Alberto Arce)