WASHINGTON – Nick Slatten’s last trial ended with him receiving a sentence of life in prison. He’s hoping his next trial will set him free. The former Blackwater Worldwide Security guard goes on trial Monday for the second time on a murder charge amid allegations that he instigated a mass shooting that killed 14 unarmed Iraqi civilians and wounded 17 others, including women and children. The shooting in Baghdad’s Nisour Square occurred in 2007 during the war between Iraq and a U.S.-led coalition. Slatten’s conviction for first-degree murder was thrown out last August by a federal appeals court because he had not been allowed to introduce evidence raising doubts about whether he fired the opening shots. A three-judge panel of the U.S. Court of Appeals in the District of Columbia ordered that he be given a new trial. Slatten, 34, who grew up in grew up in Sparta, Tenn., is incarcerated in Rappahannock Regional Jail in Stafford, Va., just outside of Washington. He declined through a family friend to comment on his new trial. But earlier this year, in interviews conducted by email with USA TODAY, Slatten insisted he was innocent and that the truth would eventually come out. “I am a POW in my own country,” he said at the time. Former Blackwater guard goes on trial for second time for role in mass shooting in Iraq It's going to get ugly here this next week.