Authorities are now investigating whether Johnson was directed by the militant groups he "liked" on social media — including the African American Defense League, the Black Riders Liberation Party, the Huey P. Newton Gun Club and the New Black Panther Party — or merely emboldened by them. "I think it's safe to say we'll leave no stone unturned," Dallas police Deputy Chief Scott Walton said. It's unclear if Johnson was merely a follower or a more active participant of those groups. Babu Omowale, co-founder of the Huey P. Newton Gun Club, a black militia that performs armed community patrols in...