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.

Since the shooting, Blackwater has renamed itself Xe Corp and has undergone a management upheaval.

Prosecutors filed the request in a way that allows them to file new charges against Slatten later.

There is no indication in the documents whether they intend to.

Dean Boyd, a justice department spokesman, said on Friday he could not say whether new charges would be filed.

Defence reaction

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

Slatten was an army sniper who served two tours in Iraq before joining Blackwater.

The trial probably will hinge on whether the Blackwater guards were provoked. Iraqi witnesses say Blackwater fired the only shots.

Some members of the Blackwater convoy said they saw gunfire. Others said they did not.

Radio logs of the shooting indicate the guards were fired on.

Prosecutors say the guards was itching for a fight and unleashed a gruesome attack on unarmed Iraqis, including women, children and people trying to escape. The convoy allegedly launched a grenade into a nearby girls' school.

The prosecutors' request could be a bad sign for the government.

Immunity deal

After the shootings, some guards spoke to investigators under the promise of immunity.

Prosecutors have been arguing in private sessions that the immunity deal did not taint the case.

The judge is considering that issue now. Jury selection in the trial is scheduled to begin on January 25.

Five guards, all military veterans, face charges. Prosecutors say the shooting was unprovoked, but Blackwater says its convoy was ambushed.

A sixth guard turned on his former colleagues and pleaded guilty to killing one Iraqi and wounding another.

The case against the remaining four guards is set for trial in February.