WASHINGTON -- The Justice Department intends to drop manslaughter and weapons charges against one of the Blackwater Worldwide security guards involved in a deadly 2007 Baghdad shooting, prosecutors said in court documents Friday.

The shooting in busy Nisoor Square left 17 Iraqis dead and inflamed anti-American sentiment abroad. It touched off a string of investigations that ultimately led the State Department to cancel the company's lucrative contract to guard diplomats in Iraq.

Iraqis have said they're watching closely to see how the U.S. judicial system handles the five men accused of unleashing an unprovoked attack on civilians with machine guns and grenades.

The court documents filed Friday say only that prosecutors have asked that the case against Nicholas Slatten of Sparta, Tenn., be dropped.

Prosecutors filed the request in a way that gives them the ability to file new charges against Slatten later. There is no indication in the documents whether they intend to. Justice Department spokesman Dean Boyd said Friday he could not say whether new charges would be filed.

The request itself was sealed, so it's unclear why the case was being dropped. But it could be a bad sign for the government. After the shooting, some guards spoke to investigators under the promise of immunity. Prosecutors have been arguing behind closed doors that the immunity deal did not taint the case.

Five guards, all military veterans, face charges in the shooting that left 17 Iraqis dead. Prosecutors say the shooting was unprovoked but Blackwater says its convoy was ambushed. A sixth pleaded guilty and agreed to cooperate with prosecutors.

Slatten's attorney, Thomas Connolly, said he could not comment on the filing but said Slatten has maintained his innocence all along.