Johnson insisted on speaking only to a black police officer when he began negotiating, Brown said. <br /> <br />He knew the route of the Dallas march, triangulating police and started taking them out with his high-caliber rifle. <br /> <br />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. <br /> <br />Brown said it was not immediately clear what those letters meant. <br /> <br />Sharpshooters could not get a view of Johnson as he hid behind a brick wall, so police used a bomb carried by a robot. <br /> <br />"I'll do it again if presented with the same circumstances," Brown said
