The recent deadly shooting attack on a group of undocumented immigrants who were traveling in a vehicle near the Arizona border alerted U.S. authorities to the presence of criminal groups in the region.
Two people died in the April 8 incident near the town of Eloy, where the truck transporting between 20 and 30 undocumented migrants was fired upon by a group of men wearing camouflage.
According to information furnished by the Pima County Sheriff's Office, the bodies of Mexican citizen Gerardo Perez Ruiz and Juan Baltazar Lopez, a Guatemalan national, were found at the scene.
Some of the immigrants who were found in the vicinity said that the attackers shouted at them in Spanish to "stop" before opening fire.
"These criminals who attacked this group are people who have no kind of morals, no conscience regarding the life of another person," Tony Estrada, sheriff of Arizona's Santa Cruz County, told Efe on Thursday.
Estrada, who has law enforcement experience with groups of criminals operating along the border, said that these bands devote themselves to stealing drugs or human "merchandise" from other traffickers.
Another possibility is that the immigrants were attacked by a group of border vigilantes, but that has not been able to be ascertained by investigators of the case.
Sheriff Estrada said the gangs that target drug smugglers and human traffickers operate in the most remote parts of the desert, in mountainous areas where there is not much law enforcement oversight.
"The target in this case are humble people; working, struggling people who come from extreme poverty, who want to survive like any other citizen and who become the target of this group of people, whether they be racist vigilantes or criminal groups," Estrada said.
The sheriff said that the ideal situation is for everyone to be able to cross the border into the United States legally to work, and he says he feels that the only solution is for comprehensive immigration reform.
This is not the first incident of its kind along the Arizona border. In 2007, two similar attacks occurred, both of them with deadly consequences.
In the first of those earlier incidents, three immigrants died during an attack on the truck transporting them to the outskirts of the city of Tucson. In the other, two undocumented immigrants lost their lives when men dressed in black fired on the truck they were riding in.
In the first case, authorities were not able to make any arrests and the motive for the attack continues to be a mystery. In the second, authorities concluded that the armed group was looking to steal drugs without knowing that the truck was transporting undocumented migrants.
Matt Allen, special investigative agent with Immigrations and Customs Enforcement in Arizona, told Efe that the agency - along with local law enforcement - has focused on fighting the activities of these criminal organizations.