Johnson insisted on speaking only to a black police officer when he began negotiating, Brown said.
He knew the route of the Dallas march, triangulating police and started taking them out with his high-caliber rifle.
At one point earlier, Johnson, apparently wounded in the exchange of gunfire with police, wrote the letters "RB" in his own blood on a wall at the community college where he was holed up.
Brown said it was not immediately clear what those letters meant.
Sharpshooters could not get a view of Johnson as he hid behind a brick wall, so police used a bomb carried by a robot.
"I'll do it again if presented with the same circumstances," Brown said
