CIUDAD JUAREZ, Mexico – On Monday afternoon, Luis Emilio realized he’d had enough.

The 22-year old Ecuadoran migrant had just spent three days in detention in the United States after seeking asylum, only to be sent back to Mexico until his immigration hearing.

The Tribune's reporting for this project is supported by the Pulitzer Center.

That meant staying in this border city until August under a U.S. government program called the Migrant Protection Protocols, which returns asylum seekers, mainly from Central America, back to Mexico to wait out their asylum bids. The program began in California in January and was expanded to the El Paso ports of entry in March.

By mid-May, about 2,800 migrants were waiting in Ciudad Juárez under the program. As of Monday, that number had swelled to more than 7,600, said Enrique Valenzuela, director of Ciudad Juárez’s Centro de Atención a Migrantes, a migrant transition facility operated by the Chihuahua state government.

The program will reportedly be expanded to other parts of the Mexican border later this month; the Associated Press reported that next likely place will be Nuevo Laredo, Tamaulipas, which borders South Texas and for years has been considered one of the country's deadliest cities.

Instead of toughing it out, Luis Emilio, who declined to give his last name, said he was going to try and scrape up enough money over the next few days and make his next move.

“I need to find some money to buy a ticket to get back to [Ecuador]; no one told me [I’d be sent back] to Mexico,” he said as he and four other Ecuadorians walked down Avenida Juárez, the city’s main street.

The MPP program also has coincided with a spike in homicides in Ciudad Juárez. In May, 151 people were killed. Over the first 17 days of June, more than 80 more homicides were recorded in the border city.

That’s caught the attention of human rights groups that have asserted that MPP fails to provide a safe haven for asylum seekers who claim they are fleeing equally dangerous conditions in their home countries.

In a 56-page report, Human Rights Watch detailed several firsthand accounts of violence experienced by asylum seekers in Mexico. They include the rape of a 20-year old Honduran woman who was told her 4-year old son would be killed if she screamed for help; a 21-year old Salvadoran who was stabbed in the back but was told local police would not help him because he wasn’t a Mexican citizen; and the kidnapping by a taxi driver of a 23-year old Honduran woman and her daughter who had to pay a ransom under threat of being killed.

Human Rights Watch also alleges that as part of the United Nations Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, the U.S. government is obligated not to return anyone to a country “where there are substantial grounds for believing that [they] would be in danger of being subjected to torture.”

“Under the Migrant Protection Protocols program, the [United States] fails to comply with its international legal obligations to ensure that asylum seekers can fairly exercise their right to seek asylum and are protected from refoulement,” the report states. Even former Mexican officials, who have in the past been reluctant to paint their country as a volatile war zone, have conceded the MPP program places migrants at risk.

During a discussion on U.S-Mexico relations at the Aspen Ideas Festival last week, Jorge Guajardo, who served as Mexico’s ambassador to China from 2007 to 2013, said Mexico isn’t a safe haven for the migrants.

“It’s not realistic; Mexico is not a safe third country, “ he said, adding that the country doesn't have the capacity to absorb large numbers of migrants.

In May, Valenzuela, the transition facility director, sounded alarm bells about a lack of shelter space in Ciudad Juárez that could force migrants onto the streets to fend for themselves. On Monday, he said the situation has only become more urgent, with migrants sent back to Mexico through MPP joined by 6,000 who are still waiting their turn to cross the border and apply for asylum.

“We do need a growing network of shelters; we need to add more shelters on a monthly basis,” he said.

The tension has spilled onto the streets of the Mexican border city. On Monday, more than 250 Cuban and Central American migrants amassed at the foot of the downtown bridge in Juárez and made their way toward the United States, demanding to be let in, TV station KTSM reported. Officials closed the bridge for about three hours and used "hardening" measures, including rolling out razor wire, adding concrete barriers and deploying Customs and Border Protection officers in riot gear, to secure the port.

Valenzuela said he wasn’t sure if any of the marchers had been returned to Mexico under the MPP program, but he worries that wouldn’t matter to frustrated Juarenses who are becoming weary of the growing number of migrants in their town.

“We are worried that this may provoke more tension. I’ve asked the migrants to avoid this type of action,” he said. “We want to preserve this orderly system we have implemented locally, and this doesn’t help.”