Four former employees of the notorious Blackwater security firm went on trial here Wednesday, seven years after allegedly killing at least 14 Iraqi civilians in Baghdad.
Backed by an army of lawyers, Paul Slough, Evan Liberty, Dustin Heard and Nicholas Slatten appeared dressed in suits and ties before a federal court in Washington for the start of jury selection.
The trial was expected to last between five and six months, Slatten's lawyer Thomas Connolly told AFP.
Judge Royce Lamberth said an unspecified "very high number" of Iraqi witnesses is scheduled to testify about what they saw on September 16, 2007 in Baghdad's Nisour Square.
The US Attorney's Office said it was believed to be "the largest group of foreign witnesses ever to travel to the United States for a criminal trial."
The Blackwater employees were guarding a US diplomatic convoy when they opened fire, killing 17 unarmed Iraqi civilians according to an Iraqi investigation, or 14, according to the US count. The hail of gunfire also wounded 18 people.
The killing exacerbated Iraqi resentment toward Americans, and was seen by critics as an example of the impunity enjoyed by private security firms on the US payroll in Iraq.
Blackwater, whose license to work in Iraq was revoked by Baghdad, was renamed Xe Services in 2009 and then Academi in 2011.
Upon President Barack Obama's arrival in office in 2009, the State Department canceled its contract with the firm.
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- Not guilty pleas -
Slatten is charged with the first degree murder of a civilian. Slough, Liberty and Heard are accused of voluntary manslaughter of the 13 other victims.
All four have pleaded not guilty.
Their trial follows a tortuous legal process that saw the case slowly wind through US courts.
In 2009, a US judge dismissed charges against five former Blackwater employees because certain statements they made immediately after the event could not be used against them.
Two years later, an appeals court reinstated the indictments against four defendants, opening the way for the current trial.
But a judge dismissed the case against Slatten in April because of a technicality. Federal prosecutors then re-filed first degree murder charges against him several weeks later.
Slatten, if convicted, faces a maximum penalty of life in prison but prosecutors would have to convince a jury that he acted with premeditation.
Before the killings, Slatten allegedly told acquaintances he wanted to "kill as many Iraqis as he could as 'payback for 9/11,'" according to court documents.
Blackwater founder Erik Prince has since separated from the company, but he wrote his memoirs about it this year titled "Civilian Warriors: The Inside Story of Blackwater and the Unsung Heroes of the War on Terror."