The man suspected of killing a suburban Chicago family — including two young kids and their three dogs — was a gun-toting security guard whose step-daughter called him a “very dangerous man.” Nathaniel Huey Jr. — who appears to have killed himself in a blazing car to evade capture for the shocking slaughter — owned a private security firm called Black Bear Security. The 32-year-old suspect was pictured on Black Bear Security’s Facebook page with guns, ammunition and body armor, with one post reading: “I can and I will.” One photo even showed him holding an assault rifle with what...