He strongly defended the decision of police to use a bomb mounted on a robot to kill the gunman, believed by criminal justice and legal experts to be the first time that USA law enforcement has used a remote controlled explosive device to kill a suspect.
Brown said that investigators are still trying to make sense of the evidence found in Johnson's home in Mesquite, though he said that they have discovered bomb-making materials, a personal arsenal, and a journal of combat tactics.
Micah Johnson, the man who shot 12 police officers, killing 5, in Dallas on Thursday night may have had grandiose plans of mayhem, according to the head of police.
Among Dallas investigators' current goals: Figure out what Johnson had meant by "RB", lettering that Brown said he'd written on the wall in blood before his death. Brown said 11 officers fired at the 25-year-old suspected Dallas sniper, Micah Johnson, and two used an explosive device.
"I appreciate critics, but they're not on the ground, and their lives are not at risk", he said.
Brown added: "This wasn't an ethical dilemma for me".
At the press conference, Brown said that the United States asks "too much" of its police and mentioned the diverse tasks of controlling the city's dog population, taking care of students with problems in some schools, along with problems of minor crime and traffic control.
"There is a heightened sense of awareness around threats we've received all over the country", Brown said.
Also on Sunday, the White House said Mr Obama would travel to Dallas on Tuesday. Police were sharply criticized in 2014 after deploying military-style guns and armor to quell protests against the killing of an unarmed black teenager in Ferguson, Missouri.
He said that police want to be "Superman" and are the last to ask for help, noting that the role of the police in society and their relationship with minorities is now under the microscope. "Which leads us to believe that he was wounded on the way up".
Johnson's military training helped him to shoot and move rapidly, "triangulating" his fire with multiple rounds so that police at first feared they were facing several shooters.
"Some of the questions we may never know the answer to", Brown said.
Earlier, Dallas Police said that officers were searching the police parking garage for a "suspicious person".
The Dallas Police have released an official statement regarding the robot used to kill one of the Dallas shooters on Thursday night. "Get out of the protest line and put an application in". "Without our actions, he would have hurt more officers".