Friendly fire was probably to blame in the fatal shooting of a federal agent and wounding of another along the Arizona-Mexico border, the FBI says.
'There are strong preliminary indications that the death of United States Border Patrol Agent Nicholas J. Ivie and the injury to a second agent was the result of an accidental shooting incident involving only the agents,' FBI Special Agent in Charge James L. Turgal said in a statement on Saturday.
Turgal didn't elaborate on the agency's conclusions but said the FBI was using 'all necessary investigative, forensic and analytical resources in the course of this investigation' into the Tuesday incident, about 8km north of the border near Bisbee.
Ivie was shot and killed after he and two other agents responded to an alarm triggered by a sensor aimed at detecting smugglers and others illegally entering the US.
One of the other agents was shot in the ankle and buttocks but released from hospital after surgery. The third was uninjured.
The Cochise County Sheriff's Office, which is assisting the FBI in the probe, said federal investigators used ballistic testing to determine the shootings were likely the result of so-called friendly fire among the agents.
Jeffrey D. Self, commander of Customs and Border Protection's Joint Field Command-Arizona said investigators were making progress but noted that despite initial findings the shootings appear accidental.
A Mexican law enforcement official said on Thursday federal police had arrested two men who may have been connected to the shootings.
The official, who spoke on condition of anonymity, said it was unclear if there was strong evidence linking the men to the case.
It was unclear on Friday whether the two remained in custody or were still being considered part of the probe.