A Dallas County jury has sentenced a man to death for the 2007 killing of a Dallas police officer.

Brian Keith Moore, 44, was convicted in October of capital murder for the shooting death of Senior Cpl. Mark Nix, who was responding to a disturbance call in the Oak Cliff neighborhood.

Nix, a 16-year veteran of the Dallas Police Department, was killed when Moore opened fire on him with a revolver. Nix had been responding to reports of a man with a gun in the area.

Moore was arrested shortly after the shooting and has been in custody ever since.

The jury deliberated for two hours before handing down the death sentence. Moore has been sentenced to death by lethal injection.

Moore’s attorneys had argued that he was not mentally competent to stand trial and that he had a long history of mental illness. However, prosecutors argued that Moore was aware of his actions and that he had killed Nix in cold blood.

Moore is the first person to be sentenced to death in Dallas County since 2005. His execution date has not yet been set.