This Blackwater shootout in Baghdad might not have gone down like the prosecution claimed

Four contractors with the security firm formerly known as Blackwater may have come under fire before they shot and killed more than a dozen Iraqis in 2007, federal prosecutors admitted in a hearing before the United States Court of Appeals in Washington, D.C.

According to a report by Circa.com, the government lawyers' admission could result in the convictions of the contractors over the deaths of 17 Iraqi civilians being overturned by the appellate court. The contractors had claimed they opened fire in self-defense during their 2014 trial.

The incident drove a deeper wedge between the American and fledgling Iraqi governments over the perception of trigger-happy security contractors running roughshod over Iraqi civil rights. Five Blackwater contractors were involved in the incident, which took place in Baghdad's Nisoor Square. Three were given 30-year sentences, one was given a life sentence and one had the charges dropped.

The prosecution's main witness, Jimmy Watson, testified during the trial that there was incoming fire, according to an August 2014 report by Bloomberg News.

"In fact, what [Watson] thought he heard was enemy fire," Demetra Lambros, the federal prosecutor arguing the case in front of a three-judge panel, allegedly admitted during the oral arguments. "[Watson is] very clear about it. Those first shots did not come from the convoy."

The contractors had been sent to secure the area in Nisoor Square where an employee of the Agency for International Development was holding a meeting after an improvised explosive device, or IED, had been detonated nearby. A vehicle that approached a convoy under their protection may have reinforced the perception that they were under attack, reports say.

"So for all these years the federal government has been painting this case as cold blooded, a cold-blooded shooting," Blackwater founder Erik Prince told Circa.com. "Here they are acknowledging, yes indeed, there is incoming fire. We've known that all along."

"This could be a major boon to the defense," Jeffrey Addicott, director of the Center for Terrorism Law at St. Mary's Law School, told Circa.com. "The appellate court could throw the entire conviction out based on that alone."

This would not be the first time that claims of an unprovoked massacre were debunked.

Eight Marines faced charges in the aftermath of a Nov. 15, 2005, firefight in Haditha, Iraq that resulted in civilian casualties. Then-Democrat Pennsylvania Rep. John Murtha, a former Marine, claimed the killings were "cold-blooded murder," according to CNN.

In the end, Reuters reported that one Marine plead guilty to negligent dereliction of duty. The Associated Press reported that the other seven Marines charges had their cases dismissed or were exonerated.