Five former Blackwater armed contractors pleaded not guilty Tuesday to federal manslaughter and gun charges stemming from the 2007 Nisoor Square massacre in Baghdad, when Blackwater guards killed seventeen Iraqi civilians and injured dozens of others. The five are charged with fourteen counts of manslaughter, twenty counts of attempted manslaughter and one count of using a machine gun to commit a crime of violence. A sixth former Blackwater contractor has already pleaded guilty and is cooperating with prosecutors. Meanwhile, in a separate case, a Blackwater contractor who fatally shot a body guard of Iraqi Vice President Adil Abdul-Mahdi will reportedly soon be charged in the killing. The shooting occurred on Christmas Eve in 2006 in the Green Zone.