Lawyers have delivered opening statements in the trial of a former Texas high school athlete who is accused of fatally stabbing a 17-year-old competitor from a rival team at a track meet. A prosecutor described it as a “sneak, surprise attack.” The killing last year stunned a Dallas suburb where the teenagers attended school and quickly drew wider attention, in part because of social media posts about race. The accused, Karmelo Anthony, is Black and the victim, Austin Metcalf, was white. Anthony's lawyer says the teen was defending himself.