Secretary of State Condoleezza Rice has ordered a high level review board in Baghdad to look at five incidents were guards from North Carolina-based Blackwater USA killed civilians in Iraq this year.
The United States has not made conclusive findings about the incidents.
Defense Secretary Robert Gates has sent a team of his own to Baghdad to investigate conditions involving private contractors working for the Pentagon.
The United States is conducting several inquiries spawned by the deadly Baghdad shooting this month involving the Moyock-based private security contractor that protects U.S. diplomats and others
The Blackwater guards insist the convoy was attacked before the protective detail opened fire. Iraqi witnesses say the gunshots were unprovoked.