The FBI has determined that the shooting incident that claimed the life of a border patrol agent and wounded a second agent was likely a case of friendly fire.
"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 of the Phoenix Field Division James Turgal said in a statement.
At about 1 a.m. Tuesday -- the middle of the night in the lonely Arizona desert near the Mexican border -- remote sensors alerted the U.S. Border Patrol that something was moving in the darkness.
According to sources familiar with the investigation, Ivie, a four-year veteran of the U.S. Border Patrol came in to take a closer look. Two other agents approached the area from an opposite vantage point to investigate.
What happened next remains unclear, but sources suggest all three agents apparently discharged their handguns, leaving Agent Ivie dead and another agent wounded.
It is not clear who fired first, but Ivie, who was alone, and the two agents he faced appeared to have fired at each other, resulting in a tragic loss of life. Sources indicated that shell casings found at the scene suggested that scenario.
It remained unclear whether Ivie and the other agents encountered someone else in the desert who may have escaped or whether Ivie believed he was returning fire to an unknown source but mistakenly engaged his fellow agents.
Bullets can carry a great distance in the desert, making for an enormous crime scene. Sources described this area as being very rugged and difficult to survey for evidence.
Homeland Security Secretary Janet Napolitano travelled to Arizona to personally express her condolences to the family of Border Patrol Agent Ivie.
Today, she toured the area where the incident took place and received a briefing on the investigation at the Brian A. Terry Border Patrol Station in Bisbee, Ariz.
That station was recently dedicated to the memory of another slain Border Patrol agent killed in the line of duty by a firearm that was part of the botched "fast and furious" firearms trafficking investigation.
"I am deeply saddened by the death our fallen colleague," Napolitano said. "This tragedy reminds us of the risks our men and women confront, the dangers they willingly undertake while protecting our nation's borders."
The investigation is ongoing, the FBI said, adding that all necessary investigative, forensic and analytical resources will be brought to bear to learn more about what went wrong.