Assistant U.S. Attorney Nathan Williams told jurors during closing arguments Thursday morning that Roof was a coward acting on a "cold, calculated hatred" for black people when he chose some of the most vulnerable to gun down as they closed their eyes to pray, the Post and Courier reported. He pointed out that the church members, led by the Rev. Clementa Pinckney, welcomed Roof into their church before he turned on them, unleashing a barrage of more than 70 bullets from the .45-caliber Glock he brought into their house of worship.