(NBC NEWS) - Investigators are preparing to announce that the death of Border Patrol Agent Nicholas Ivie in Arizona earlier this week was the result of friendly fire -- accidental gunfire from another agent who responded to the same scene, state and federal officials told NBC News on Friday.
The conclusion is based on an analysis of the ballistics, the lack of evidence of other criminals in the area at the time, and other factors, the sources said.

A formal statement about the findings could come later Friday.

The incident involving Ivie and two other agents occurred Tuesday in a rugged area about five miles north of the US-Mexico border near Bisbee, Ariz. The agents had responded to an alarm from a sensor that tracks illegal movement along the border.
Ivie was killed. A second agent was wounded and was released from the hospital after undergoing surgery. The third agent was unharmed.

State and federal officials said immediately after the incident that the shootings were committed by armed criminals. And since then, Mexican authorities have said they arrested two men in Agua Prieta, northern Sonora state, a few miles from where the shooting occurred.