DALLAS, July 10 (UPI) -- Dallas sniper suspect Micah Xavier Johnson wrote letters in his own blood on a wall in the room where he was holed up, then later killed by a police-deployed robot, police said.
Dallas Police Chief David Brown said it was not clear what the letteringR B meant and investigators are still trying to figure it out, he said on CNN Sunday. Brown said they believe he must have been wounded as he shot his way in to El Centro College where the sniper attacks took place.
And, Brown said on State of the Union, "We are convinced this suspect had other plans and thought that what he was doing was righteous and believed that he was going to target law enforcement -- make us pay for what he sees as law enforcement's efforts to punish people of color."
Police acknowledged Saturday they have found rifles, ammunition and bomb-making materials at Johnson's Mesquite home. That leads investigators to believe he had bigger plans.
The chief said Johnson, a member of Army Reserve who had been sent home from Afghanistan following a sexual harassment complaint, kept a journal filled with "quite a bit of ramblings" on combat tactics.
Brown killed five police officers July 9 at the end of what had been a peaceful protest against recent shootings by police that led to the deaths of several black men.
Johnson reportedly told negotiators he was upset about those recent police shootings and he wanted to kill white people and specifically, white police officers, the Dallas Morning News reported.
Brown confirmed that Johnson asked during negotiations with police to speak only to an African American negotiator. Brown did not make it clear whether they obliged Johnson.
He said his department has not ruled out whether others were "complicit" in the sniper attack.
Police kept a number of streets around El Centro College, where Johnson had holed up, stretched with yellow crime scene tape over the weekend. A team of some 70 evidence experts from the FBI's Dallas field office combed the streets for evidence, FBI spokeswoman Allison Mahan said.
She said the Dallas Police Department has the lead in the investigation and most of the evidence will be turned over to that department.
"We continue to provide all available resources and personnel in support of DPD," Mahan said, "to include agents from numerous investigative squads as well as investigative analysts, crisis management specialists, and victim assistance specialists, to name a few."
Brown, during his Sunday interview with CNN, sent a message to protesters in other cities.
"We're sworn to protect you and your right to protest, and we'll give our lives for it," Brown said. "And it's sort of like being in a relationship where you love that person, but that person can't express or show you love back," he said. "I don't know if you've been in a relationship like that before, Jake, but that's a tough relationship to be in, where we show our love -- because there's no greater love than to give your life for someone, and that's what we're continuing to be willing to do."
"And we just need to hear from the protesters back to us, 'We appreciate the work you do for us in our right to protest,'" Brown said. "That should be fairly easy."