CHARLESTON, S.C., Dec 7 (Reuters) - Avowed white supremacist Dylann Roof said he had to kill innocent black South Carolina churchgoers at a Bible study last year in retaliation for perceived offenses against his race, a prosecutor said in opening statements at Roof's federal death penalty trial on Wednesday.
As the trial began at the J. Waties Waring Judicial Center, lawyers warned jurors to brace themselves for a recounting of the massacre in which nine people died at Charleston's historic Emanuel African Methodist Episcopal Church on June 17, 2015.
"He chose to enter the religious sanctuary and sit with the parishioners for half an hour, coldly considering what he was about to do," Assistant U.S. Attorney Jay Richardson said of Roof in his opening statement.
Roof, 22, faces 33 federal counts of hate crimes resulting in death, obstruction of religion and firearms violations stemming from the attack. He also is scheduled to be tried for murder by state prosecutors.
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Richardson said Roof scouted the church for months. He bought a gun in April 2015 and began stockpiling ammunition and performing target practice.
On the muggy June night he carried out his plan, Roof waited until parishioners stood to pray at the end of their meeting before opening fire with his .45-caliber pistol, the prosecutor said.
His first target was the Reverend Clementa Pinckney, the church's pastor and a state senator who had offered Roof the seat beside him at the Bible study. Then he fired round after round into each of his victims.
"You don't have to do this. We mean you no harm," a wounded Tywanza Sanders, 26, told Roof, according to Richardson.
Spouting white supremacist views, Roof then shot and killed Sanders, the prosecutor said.
Roof told Polly Sheppard, who was praying out loud, that he would let her live to tell the story of what he had done.
He confessed to the killings to federal agents when he was apprehended in North Carolina after an overnight manhunt.
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Richardson said Roof had been spreading his message before the shootings by publishing an online racist manifesto and writing in his journal about his hopes for a race war.
Sheppard and Felicia Sanders, who also survived along with her 11-year-old granddaughter, will testify against Roof, Richardson said.
Defense attorney David Bruck told jurors the facts of the crime were not in dispute and began laying the groundwork to argue for a life sentence rather than execution, asking the jury to focus on what factors drove Roof to commit an act that made no sense.
"By my count, (Roof) said, 'I had to do it' about 10 times. What does that suggest to you?" Bruck asked. "Watch carefully his dispassionate affect and ask yourself what that means."
Roof, who served as his own lawyer for about a week during jury selection, has told U.S. District Judge Richard Gergel he wants to act as his own counsel again during the sentencing phase of the trial.
He also will face the death penalty in his state murder trial, which is scheduled to begin early next year.