OAXACA CITY: A week after 53 migrants died in a sweltering trailer in San Antonio, Texas, some of their nationalities are still unclear, highlighting the challenges that officials from at least four different countries face in identifying the victims of the deadliest U.S. human smuggling tragedy on record.

The information trickling from various governments has been marred by confusion and discrepancies, as officials scramble to identify the victims using ID cards, passports and documents found in the trailer, fingerprints, and photos provided by family members.

The governments of Mexico, Guatemala and Honduras say they have already identified at least 49 migrants who were in the truck.

But according to Bexar County, where the tragedy occurred, only 35 victims have been definitively identified. It had conclusively identified 20 Mexicans, 10 Guatemalans and five Hondurans as of Tuesday, according to spokesperson Tom Peine, who added the medical examiner's identification criteria is often more stringent than that of other governments.

Migrants who die in the borderlands frequently don't carry identification, said Cesar Ortigoza, president of Armadillos Ni un Migrante Menos, a binational organization of volunteers who search for missing migrants along the U.S.-Mexico border. Sometimes the identification process takes months or years, Ortigoza said.

People smugglers "often tell the migrants, 'Look, if you carry identification, throw it out, because if the police arrest you, they will detain you and know who you are,'" Ortigoza said. "For that reason, it's difficult to find the identities."

In some cases, government officials have also struggled to find and communicate with relatives of the San Antonio victims who live in remote areas or speak indigenous languages, advocates and officials said. 

CONFUSION AND DISCREPANCIES

Much of the confusion about nationalities stems from a Mexican news conference last Wednesday in which the head of Mexico's national migration institute, Francisco Garduno, said that 27 Mexicans had died, along with 14 Hondurans, seven Guatemalans, and two Salvadorans.

The Honduran and Salvadoran governments have since said those figures are inaccurate.

Honduran authorities released the names of six Hondurans found in the trailer, saying they are unaware of the source of Garduno's number. El Salvador's foreign affairs ministry told Reuters on Monday that they know of no Salvadoran victims. Meanwhile, Guatemalan authorities have released the names of 16 deceased Guatemalans identified through fingerprints.

A spokesperson for Mexico's foreign ministry did not clarify the source of Garduno's information, but said the number of Mexicans who died in the trailer remains unchanged.

The Bexar County medical examiner has been slower to publish its conclusions on the victims' nationalities.

"There is nothing worse than a wrongful identification," spokesperson Peine said.

Several false identifications have circulated already.

The day after the tragedy, Mexican Foreign Minister Marcelo Ebrard posted to Twitter a photo of two Mexican voter credentials found in the trailer. One of the people identified in the tweet, Haneydi Yasmin Antonio from southern Mexico, soon posted on Facebook that she was fine. She said her ID had been stolen the year prior.

Meanwhile, two Guatemalan girls identified on social media as potential victims had in fact drowned in the Rio Grande, said Karla Samayoa, a spokesperson for Guatemala's foreign ministry.

The void of reliable information has left families across Mexico and Central America anguished as they await news of loved ones.

Alvaro Enrique Ojeda's family last heard from him on June 23, when he told them he was waiting in a house in Texas to get onto a trailer with 50 other people, said his sister Maria Guadalupe Ojeda in a Facebook video.

Without any word from the Mexican government, they held out hope that he might be hospitalized or detained, even as Texas mourners mounted a wooden cross bearing Ojeda's name near where the trailer was discovered.

On Monday, a week after the tragedy, Mexican authorities contacted Ojeda's family to do a photographic identification of Ojeda's body, said Omar Hernandez, a migrant advocate who has supported the family.

"At least now they know where he is," Hernandez told Reuters. "They no longer have uncertainty."