Five guards from Blackwater security firm were charged Monday by U.S. authorities for killing 14 Iraqi civilians last year.
The defendants surrendered to authorities and will appear later in a federal court in Salt Lake City, Utah.
But the U.S. government said it intends to try them in Washington, where support for the war in Iraq isn't likely to be as strong as in the Western state.
The manslaughter and weapons violations charges against the five defendants carries a mandatory minimum prison term of 30 years and the penalty for manslaughter is 10 years, officials said.
U.S. Assistant Attorney General Patrick Rowan and other federal officials said that the charges serve as "a reminder" that anyone who engages "in unprovoked attacks will be held accountable."
A sixth Blackwater guard pleaded guilty last week to voluntary manslaughter and related charges.
The Blackwater firm which wasn't charged in the case, argued in a statement that the defendants "acted within the rules set forth for them by the government."
On Sept. 16, 2007, at least six Blackwater guards opened fire with automatic weapons and grenade launchers on unarmed Iraqi civilians in Baghdad after a car bomb exploded.
The U.S. government accused the guards of causing the deaths of14 unarmed civilians and injuring 20 others. Three other fatalities weren't included in the charges.
None of the victims were insurgents and many were shot while inside their cars as they attempted to flee the scene, the indictment said.
After the incident, the U.S. government began investigating Blackwater, a private security contractor hired to protect State Department personnel in Iraq.
Following that, Defense Secretary Robert Gates and Secretary of State Condoleezza Rice announced procedures for closer oversight and accountability for almost 10,000 private security personnel in Iraq.