A “real quiet” kid who kept to himself. An aspiring YouTube rapper. A face etched with tattoos. Robert Crimo III was a mystery to his own family, according to his uncle who was both deeply apologetic and stunned after the 22-year-old was taken into custody as a person of interest in the Highland Park parade shooting in Illinois. As police dove into their investigation of the shooting attack that shattered the celebratory spirit at the Fourth of July parade, killing six people and injuring more than two dozen others, disturbing details began to emerge about Crimo. “There were no warning signs,”...