What he did, according to Dallas police, was open fire near a peaceful protest in downtown Dallas on Friday, killing five law enforcement officers, including a Dallas-area transit officer.
"He was upset about the recent police shootings" and "wanted to kill white people, especially white officers," he told police as they were trying to get him to surrender, according to Dallas Police Chief David Brown.
Ultimately, he was killed by a bomb-carrying robot deployed and then detonated by police on the second story of a building where they had cornered him.
"Just snapped" was also the only explanation another neighbour in Mesquite, Sandra Johnson, could come up with.
"This a very nice community," Johnson said. "Something must have happened to that young man. He was in the military. Maybe he just snapped."
Blanton, who is black and has a brother who is a transit police officer, said she believes the shootings in Baton Rouge, Minnesota and elsewhere of African-Americans "sent him off."
Blanton said the Johnsons were a close family. Although Johnson's parents were divorced, his father would come to the house every two weeks and mow the grass at the house. Johnson's paternal grandfather, also lived at the home until his death a few years ago.
"They are a loving family. His mother would speak to everyone," Blanton said.
Something must have happened to that young man. He was in the military. Maybe he just snapped
Blanton said she remembered when someone broke into the Johnson's home and stole his five assault rifles for which, Johnson said, he had a license.
She said she was not concerned living next to Johnson knowing he had the rifles.
"Texas is an open carry state. Everyone has some type of gun here," she said.
Rifles, police discovered, were not the only combat gear he kept in the home. They said they discovered bomb-making materials, ballistic vests, rifles, ammunition and a personal journal detailing combat tactics.
Blanton said she often saw Johnson walking around the neighbourhood wearing a white T-shirts and gym shorts. He would often play basketball, she said, at the local basketball court with youth and men from the neighbourhood.
"I think he just got tired. Tired of what this nation is putting us through as a people, as a culture," she said.