Wild, unprovoked gunfire and grenades killed 14 innocent Iraqis and hurt dozens more in a 2007 Baghdad attack, prosecutors said on Monday in announcing charges with mandatory 30-year prison terms against five Blackwater Worldwide security guards.
The US Justice Department called the shooting a shocking and devastating violation of human rights.
The harsh words echoed the outrage of Iraqis, who have waited more than a year to see how the United States would respond to the shooting on a busy street in the Iraqi capital.
The shooting by the largest U.S. security contractor in Iraq sparked international condemnation, launched congressional hearings and inspired anti-American insurgent propaganda.
The five security guards, all decorated military veterans, surrendered in federal court in Utah, where one of them lives.
The five guards walked wordlessly through a phalanx of reporters.
A judge ordered the guards to report to a Washington courthouse on January 6, where they were expected to plead not guilty.
A sixth Blackwater guard struck a deal with prosecutors, turned on his former colleagues, and pleaded guilty to killing one Iraqi and wounding another.
Prosecutors said the slain included young children, women, people fleeing in cars and a man whose arms were raised in surrender as he was shot in the chest.
Twenty others were wounded in crowded Nisoor Square, including one injured by a grenade launched into a nearby girls' school.
Another 18 Iraqis were assaulted but not wounded, prosecutors said.
Blackwater, which was not charged in the case, maintains its guards were protecting themselves from what they believed was an imminent car bomb attack.
The five guards were charged with 14 counts of manslaughter, 20 counts of attempted manslaughter and one count of using a machine gun to commit a crime of violence. The machine gun charge, typically used in drug cases, carries a 30-year minimum prison sentence.
In all, 17 Iraqis were killed in the assault. But a US Assistant Attorney said evidence in the case could only prove the guards shot 14, although he left open the possibility of future charges.
The guards are Donald Ball, Dustin Heard and ; Evan Liberty, all inactive U.S. Marines; and Nick Slatten, a former Army sergeant, and Paul Slough, another Army veteran.
Defence lawyers say the case has tarnished unfairly the images of the Blackwater guards. Each man has received honours for his service in some of the world's most dangerous places, from Bosnia and Afghanistan to Iraq.
The sixth guard, who is cooperating with the government, is Jeremy Ridgeway, who pleaded guilty to one count each of manslaughter, attempted manslaughter, and aiding and abetting.
In his plea agreement with prosecutors, Ridgeway admitted there was no threat from a white Kia sedan whose driver, a medical student, was killed and his mother, in the front passenger seat, was injured.
The shooting took place around noon on September 16, 2007, in a crowded square where prosecutors said civilians were running errands, getting lunch and otherwise going about their lives.
Following a car bombing elsewhere in the city, the heavily armed Blackwater convoy sought to shut down an intersection.
Prosecutors said the convoy, known by the call sign Raven 23, had violated an order not to leave the U.S.-controlled Green Zone.
Witnesses said the contractors opened fire unprovoked, and left the square littered with blown-out cars.
The drama is far from over. After more than a year of investigative missteps and fierce debate, the Justice Department now faces stiff challenges to the evidence and legal grounds at the heart of its case.
Most importantly, prosecutors must prove they did not rely on protected statements the guards gave to State Department investigators within hours of the shootings.
The State Department gave limited immunity to all the guards in the four-car convoy, promising not to prosecute them based on the initial statements recounting how the violence began. The move left Justice Department and FBI investigators with a crime scene long gone cold and with limited forensic evidence to bolster their case.
Defence attorneys also will argue that the guards cannot be charged under a law intended to cover soldiers and military contractors since the men worked as civilian contractors for the State Department. Rowan, however, said Blackwater was supporting the military's mission in Baghdad and the law therefore applies to them.
It is the first time prosecutors have used that argument to prosecute contractors.