FBI probes fatal shooting over U.S. border into Mexico

MEXICO CITY (Reuters) - The FBI has opened an investigation into the death of a Mexican citizen, who the Mexican government alleges was shot over the Rio Grande River by a U.S. Border Patrol agent, U.S. officials said Monday.

The victim was hit by a single bullet on Saturday, close to the Tomates-Veterans border crossing in Matamoros, Mexico, over the border from Brownsville, Texas, according to the Mexican government.

U.S. agents are cooperating in the probe of the death, although they do not know if they fired the gun that killed the victim, Enrique Mendiola, spokesman for the Border Patrol's Rio Grande Valley sector said.

Mendiola believes the victim was a 29-year-old male, but Mexican officials have released no details.

On the Saturday when the killing happened, two agents had fired their service guns into Mexico at approximately the same time and near one another, Mendiola said.

The first agent had responded to someone throwing rocks at him, while the second agent had responded to someone aiming a weapon at him, Mendiola said.

Mendiola said that agents are permitted to respond to rock attacks with their guns and to fire into Mexico.

"A rock could be considered a lethal weapon and we are going to respond. Agents have been very badly injured by rock attacks," Mendiola said. "Our agents are highly trained and regardless of where the threat is coming from, our agent is going to respond to neutralize it."

Mexico's Foreign Ministry released a statement on Sunday condemning the killing and demanding an investigation.

"The Mexican government has reiterated that the disproportionate use of lethal force in immigration control is unacceptable under any circumstances," it said. "Protocols of the federal forces in both countries have to be respectful of human rights."

There have been several previous incidents of Border Patrol agents shooting Mexicans in U.S. territory but it is rare for them to shoot into Mexico.

(Reporting by Ioan Grillo; Editing by Cynthia Osterman)