The jury that began deliberating Thursday returned to the courtroom Monday and told U.S. District Judge Robert G. Doumar they were evenly divided and unable to reach a decision on the charges, the Newport (Va.) Daily Press reported.
Christopher A. Drotleff, of Virginia Beach, Va., and Justin H. Cannon, of Corpus Christi, Texas, are charged in the killings and face life in prison if convicted, the newspaper said.
In trial testimony, jurors heard opposing versions of the shooting by the two contractors on May 5, 2009 in Afghanistan.
Drotleff and Cannon said they fired in self-defense on a car approaching them in a threatening manner.
But Justice Department prosecutors said the vehicle posed no threat and that the men concocted the story to cover themselves.
After declaring a mistrial, Doumar said a retrial would be scheduled for March 2011.