A State Department review of the incident recommended the creation of a "Go Team" to prevent future investigations from being compromised by preserving evidence and interviewing witnesses quickly after an incident occurs. The team also would conduct preliminary investigations into weapons discharges and the provision of condolence payments to victims' families.
The move to staff the FIU "Go Team" with contractors appears to contradict statements made earlier this year by the top State Department official who headed the review. Asked by reporters if the teams would be staffed by contractors, Ambassador Patrick Kennedy replied, "No, no, the [FIU] Go Teams are composed of State Department employees."
The hiring of investigative contractors has raised concerns in Congress.
In a recent letter to Secretary of State Condoleezza Rice, obtained by ABC News, Sen. Russell Feingold, D-Wis., called the move to hire contractors for the FIU "highly troubling" because it called into question "the department's commitment to improving oversight of its contractors."
He urged cancellation of the contract and manning the FIU solely with government personnel.
"Anything less will further exacerbate tensions within Iraq and the region caused by our perceived failure to hold U.S. contractors accountable for misuse of force against civilians," Feingold added.
Feingold's letter also raises concerns about the admissibility in court of evidence not gathered by law enforcement personnel.
"The presence of contractors in the Force Investigation Unit could jeopardize this responsibility and undermine the perceived impartiality of the investigation unit," the letter says.
Feingold's office says it has not yet received a response from the State Department.
After the shooting in Nisoor Square, the State Department implemented a number of changes in convoy operating procedures, including the placement of cameras in all convoy vehicles to document potential incidents and a requirement that all department convoys in Iraq must be accompanied by a Diplomatic Security agent.