The former high school football player with the lightning speed often jogged for miles near the southeastern Georgia enclave where he grew up. Ahmaud Arbery's runs set him free from the blue-collar coastal city of Brunswick, where 56% of its 16,000 residents are black and more than a third of the population lives in poverty. In high school, Arbery was so fast coaches had him slow down during practices. Now 25, his athletic gait delivered him beyond the arbitrary borders of his community. Wanda Cooper, Arbery's mother, may have occasionally worried about him but never about his running. On February...