The State Department has confirmed it has secretly granted immunity to the Blackwater guards involved in last month’s mass killing of 17 Iraqi civilians in Baghdad. According to ABC News, the Blackwater guards signed agreements that read in part: “I further understand that neither my statements nor any information or evidence gained by reason of my statements can be used against me in a criminal proceeding.” The State Department says Blackwater guards can still be subjected to future prosecutions. But legal experts say convictions could be difficult because prosecutors would have to prove they did not use the sworn statements to prove their case. The protections are said to be commonly used in official investigations of incidents involving government employees. But Democratic senators say extending the immunity to private contractors is unprecedented. Meanwhile, the Pentagon has announced the U.S. military will now increase its control over private security contractors in Iraq. But it remains unclear which laws — if any — could be used to hold the Blackwater guards accountable.