The 22-year-old man suspected of shooting five middle-aged white men since last year — including four on south Kansas City walking trails — threatened in 2014 to shoot up a school and “kill all white people,” according to court records...All five were white men between ages 54 and 67. All five were fatally shot, most from behind, in surprise attacks as they walked dogs, visited parks and, in one case, walked down a city street.