The US Supreme Court on Friday threw out the conviction of an African-American man who was tried six times for a quadruple murder, saying the exclusion of black jurors was unconstitutional. Curtis Flowers, 49, was convicted in 2010 and sentenced to death for the July 1996 murders of four people in a furniture store in Winona, Mississippi, where he had briefly worked until being fired. The nation’s highest court did not examine the guilt or innocence of Flowers but whether the district attorney deliberately sought to keep black people off the jury in his most recent trial.