WASHINGTON (AP)  A federal grand jury is said to be investigating the role of Blackwater Worldwide security guards in the shooting deaths of 17 Iraqi civilians in Baghdad.

The Blackwater guards involved in the Sept. 16 shooting at Nisoor Square in west Baghdad initially were 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.

Blackwater contends that its convoy was attacked before its guards opened fire, but the Iraqi government's investigation concluded that the shootings were unprovoked.

The Justice Department has declined to comment on whether a grand jury has been impaneled to hear the case, but ABC News reported Monday that a number of Blackwater security guards have been subpoenaed to appear before the panel here next week.

A Blackwater spokeswoman, Anne Tyrrell, declined to comment Monday on whether the company had received subpoenas or whether its employees had been asked to testify.

"We have always supported stringent accountability for the industry, we still do, and if somebody was complicit in wrongdoing we would want that person to be held accountable," Tyrell told The Washington Post. "We will cooperate with any inquiry or investigation and will withhold further comment until the results are complete and made available."

ABC said it had obtained statements given to State Department diplomatic security agents. According to the statements, only five guards acknowledged firing their weapons in the incident. Twelve other guards witnessed the events but did not fire, according to the statements.

Officials cautioned that the decision to begin a grand jury inquiry did not mean that prosecutors had decided to charge anyone with a crime in what they said was a legally complex case, The New York Times reported. Some government lawyers have expressed misgivings about whether a federal law exists that would apply to the actions Blackwater employees are accused of committing, the Times reported.

Iraq, meanwhile, is demanding the right to prosecute the Blackwater bodyguards. The Iraqi government finding that Blackwater's men were unprovoked echoed an initial incident report by U.S. Central Command that indicated "no enemy activity involved" in the incident. The U.S. Central Command oversees military operations in Iraq.

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