A federal grand jury is reportedly investigating the role of Blackwater security guards in the shooting deaths of 17 Iraqi civilians.
The Justice Department and Blackwater aren't commenting on an ABC News report that some Blackwater security guards have been subpoenaed to appear before a grand jury in Washington next week.
An Iraqi government investigation concluded that the September shootings were unprovoked. Blackwater contends that its convoy was attacked before its guards opened fire.
The guards were initially given limited immunity from prosecution by State Department investigators in exchange for their statements about what happened.
One senior FBI official close to the investigation told The Associated Press last week that he was aware of evidence that could indicate 14 of the shootings were unjustified.