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(CNN) – As President Obama sends troops to Iraq, one of the uglier chapters from previous U.S. involvement is playing out in a courthouse in Washington, D.C.
After years of delay and legal issues, the U.S. government is trying four guards with the company once known as Blackwater, for a deadly shoot out in the streets of Baghdad back in September 2007.
One is charged with first-degree murder, and the other three with voluntary manslaughter, attempted manslaughter, and weapons charges.
Blackwater said their convoy came under attack. But witnesses said the guards fired first, without provocation.
"I remember people strewn on the street, children, elderly men, this is what I saw with my own eyes. The street turned into the street of the dead," one witness said.
Prosecutors say 14 Iraqi civilians were killed that day at Nisour Square, including a 9-year-old boy.
And now, a bombshell revelation by The New York Times this week – the top Blackwater employee in Baghdad allegedly threatened the life of a State Department investigator looking into the group's activities just weeks before the shooting.
The State Department memo revealed by the Times accused a Blackwater manager of allegedly telling the investigator, who was looking into the work Blackwater did, that "he could 'kill me' and no one could or would do anything about it while we were in Iraq."
The State Department investigator, Jean Richter, was reportedly stunned when officials at the embassy allegedly sided with Blackwater, and told him to leave the country. Blackwater had a $1 billion government contract to protect American diplomats.
Richter could not be reached for comment when CNN reached out to him Tuesday.
But his investigation of the company concluded that the company had insufficient oversight and created "an environment full of liability and negligence."
The State Department this week was asked if the contract review was canceled because of the alleged threats to the investigator.
"As I understand, there were steps taken at the time based on threats people on the ground faced. I don't have anything additional on that," State Department spokesperson Jen Psaki told reporters.
Much has changed in Baghdad since the days when contractors from companies like Blackwater were as common as soldiers on the streets.
In 2007 congressional hearings were held on possible misconduct by Blackwater, and then-owner Erik Prince was vilified by Congress.
"I believe we acted appropriately at all times," Prince testified before Congress.
"Blackwater seems to have fostered a culture of shoot first, sometimes kill, and ask questions later," Rep. Elijah Cummings, D-Maryland, said at one hearing.
Prince sold the company in 2010 for $200 million.
Blackwater has since undergone two name changes in apparent attempts at image rehabilitation.
But the trial and this newly revealed memo bring up new questions.
"Blackwater officials are facing the U.S. justice system, that same can't be said for State Department officials, some of whom who failed to see the red flags of all of this negligent behavior taken on by the contractor, that could have alerted us that these guys needed to be fired," said John Hudson.
"They needed to be removed from the embassy in Baghdad because they couldn't be trusted to carry out their job," he said.
That State Department memo threatening an investigator came out just days before the slaughter in Nisour Square.
The trial of the four former Blackwater guards is expected to last months. Federal prosecutors say the guards murdered the Iraqi civilians without provocation.
Defense attorneys have claimed in court that witnesses fabricated their stories. Prior to this trial, in 2009, a judge threw out an indictment against the guards.