Police in Dallas are trying to piece together what happened in the deadly attack on police officers last week -- downloading and poring over 170 hours of video and trying to get to the bottom of initials "R.B." scrawled by suspected gunman Micah Johnson in two locations during his final hours, Dallas Police Chief David Brown said this morning.
"We don't know the scope of his plans yet," Brown said.
"We're going to follow every lead until it's exhausted, until I'm satisfied this was the lone person," Brown said. "I may be overly concerned about this but I'm highly protective of cops and I want to make sure there's nobody else out there that has something to do with this."
Brown said he and his family received death threats almost immediately after the Thursday night attack, which left five officers dead nine others injured.
"My particular threat was a post from a private Facebook to our Dallas Police Department Facebook," he said. "We've been unable to identify the source of the threat but we're taking it very seriously."
"As a policing family here in Dallas and across the country, there is a heightened sense of awareness around threats we received all over the country," he said.
"I don't want to just single out me. Everyone's experiencing the same type of awareness, increased awareness, because of people who, in my opinion, are not stable, who could do grave damage to us. So we're all on edge," he said.
The suspected gunman opened fire on cops during a protest against police brutality in Dallas last week. Police said he was looking to kill white people, especially police officers and was upset about two recent, fatal police-involved shootings.
He was killed by police after a standoff using a bomb delivered by a robot.
The bomb technician said the gunman wasn't a novice and "knew what he was doing," Brown told reporters today.
Brown said 13 officers used force against the suspect -- 11 officers used their firearms and 2 officers who used the explosive device.
The robot used to deliver the explosive device was purchased in 2008 for approximately $151,000. Brown said there's partial damage to the extension arm of the robot but it is still functional for potential future operations.
In the wake of the attack, Brown said counseling services is important for his officers.
"We're the last to say we need help," Brown said.
Funeral services for three of the slain officers have been set for this week, the Dallas Police Department said. Arrangements for the other two officers are pending.
Looking beyond Dallas, Brown said today, "We're asking cops to do too much in this country."
"Every society of failure, we put it off on the cops to solve. Not enough mental health funding. Let the cop handle it. Not enough drug addiction funding. Let's give it to the cops," Brown said. "Seventy percent of the African-American community's being raised by single women. Let's give it to the cops to solve that as well. That's too much to ask. Policing was never meant to solve all those problems."
"I just ask for other parts of our democracy, along with the free press, to help us. To help us and not put that burden all on law enforcement to resolve," he said.