WASHINGTON: Lawyers for Blackwater security guards argued Monday that the government has suppressed evidence favorable to defendants who are on trial in the killings of 14 Iraqis in Baghdad’s Nisoor Square.

The attorneys say the suppressed evidence consists of photographs of eight spent shell casings that would fit an AK-47 — the weapon of choice used by insurgents as well as Iraqi authorities.

A court filing by the defense attorneys says the photographs were made by a US Army captain and that they never saw the light of day until federal prosecutors turned them over last Wednesday.

The photos could become an important part of the case. They could bolster the accounts of the security guards, who say they were being fired upon by insurgents and that the guards were simply returning fire.

“The government has suppressed, for seven years, evidence in its possession that is plainly exculpatory on the central disputed issue” in the case, the defense lawyers said in a court filing. “Had they possessed these photos, defendants would have made them a central focus during opening statements as evidence of incoming fire. Defendants also would have used this evidence to cross-examine at least four witnesses who have already testified” and who are not subject to being recalled because they have returned to Iraq.

The defense attorneys are asking that they be allowed to explain to the jurors in the case why they are just hearing now about the new evidence. The defense lawyers also want the judge to tell the jurors that the government failed to disclose the evidence before the trial, which began over a month ago.

According to the court filing, Army Capt. Peter Decareau was one of the first Americans to arrive at the Nisoor Square crime scene, where he took photos, including two of a group of eight AK-47 shells on the ground behind a bus stop. On Oct. 12, 2007, Decareau turned over to the FBI a CD of the crime scene photos.

In their court papers, the defense lawyers for the Blackwater guards say a prior team of prosecutors in 2008 and 2009 “withheld Decareau’s photographs of the AK-47 shells.” On Feb. 13, 2009, the government told the defense lawyers that it was providing over 3,700 photographs of the crime scene.

“Despite specifically identifying ... a series of ‘US Army photos of crime scene,’ this production did not include Decareau’s photographs of the AK-47 casings at the bus stop,” the defense court filing states. “The original trial team produced additional photographs on July 27, 2009, but again did not produce the photos of the AK-47 casings.”