PHOENIX -- A Mexican man pleaded guilty in federal court in Tucson Tuesday to the killing of a U.S. Border Patrol agent during a 2010 firefight near the Arizona-Mexico border, marking the first conviction in the agent's death.
Prosecutors agreed not to seek the death penalty against Manuel Osorio-Arellanes, who could face life in prison for his first-degree murder plea in the death of Border Patrol Agent Brian Terry.
The deadly shooting has prompted congressional probes of a bungled government gun-smuggling investigation known as "Operation Fast and Furious."
Two rifles bought by a gun-smuggling ring that was being monitored through "Fast and Furious" were found at the scene. But authorities have declined to say whether the murder weapon was linked to a purchase from the operation.
Terry and other agents came under attack in a canyon north of the Arizona border city of Nogales by Osorio-Arellanes and four other men who had come to the U.S. to rob marijuana smugglers, investigators have said. Authorities have declined to say which of the five men fired the shot that killed Terry.
Osorio-Arellanes, of El Fuerte in the Mexican state of Sinaloa, was shot during the gunfight and has been in custody since the night of the shooting. Osorio-Arellanes told investigators he raised his weapon toward the agents during the shootout but didn't open fire, the FBI said.
As part of the plea, Osorio-Arellanes acknowledged sneaking into the U.S. from Mexico with others about a week before Terry's death. Group members retrieved guns and food supplies that they had hidden in the United States near the border for the robberies.
Of the four other men charged in Terry's death, one is in custody, while three others remain fugitives.
Authorities have offered a $1 million reward for information leading to their capture. FBI said it continues to aggressively pursue the three fugitives.