Mexico's government on Wednesday condemned a fatal shooting by a U.S. Border Patrol agent of a Mexican man who was allegedly trying to sneak across the border.
The Foreign Relations Department urged U.S. authorities to conduct a thorough investigation of the death.
Its statement questioned the U.S. officer's "use of firearms to repel an attack with stones," calling that "a disproportionate use of force."
U.S. Border Patrol spokesman Steven Pitts has said the Border Patrol agent fatally shot a migrant Tuesday night at the U.S.-Mexico border as the man was about to hit another officer with a concrete slab. U.S. officers are generally permitted to use lethal force against rock throwers.
Mexico identified the dead man as Jose Alfredo Yanez, 40. Police in Tijuana, across the border from San Diego, said Yanez was shot once in the torso and once in the head and died on Mexico's side of the border.
Another man, presumably Mexican, was attempting to cross the border illegally with Yanez when the fatal shooting occurred a mile west of the San Ysidro border crossing, Pitts said. That man returned safely to Mexico, Mexican police said.
San Diego police are leading the investigation into the incident.
In December, the Mexican and U.S. governments issued a joint declaration saying they would work together in an effort to prevent this kind of violence in the border region.
Border Patrol agents have fatally shot rock throwers before.
A year ago on the border between Ciudad Juarez and El Paso, Texas, a U.S. officer shot a 15-year-old Mexican boy dead who was trying to cross into the U.S., investigators have said. The FBI said the agent fired his gun while repelling an attack with rocks.
The family of the boy, Sergio Adrian Hernandez Guereca, filed a lawsuit in El Paso that seeks $25 million in damages from the U.S. government.
Mexico's government offered to help the family Wednesday, including providing "necessary legal backing," the Foreign Relations Department's statement said.