-- The robot-delivered bomb used to kill a suspect in the Dallas ambush as he barricaded himself in a building during a standoff with cops appears to be the first the tactic was employed, experts say.
It made "perfect sense" for Dallas police to use a robot to stop the suspect, Micah Xavier Johnson, said David Klinger, professor of Criminology and Criminal Justice at the University of Missouri-St. Louis.
When police attempted to subdue the suspect -- who in this case killed and injured several people, according to police -- the goal was to resolve the situation with no further loss of innocent life, Klinger said.
When a situation requires deadly force, police have been known to use any means possible to apply it, such as running a suspect over, in order to protect the live of themselves or others, Klinger said.
"As a legal matter, the choice of weapon in a decision to use lethal force does not change the constitutional calculus, which hinges on whether an individual poses an imminent threat to others, and whether the use of lethal force is reasonable under the circumstances," Stanley said. "Remote uses of force raise policy issues that should be carefully considered and addressed by our society as technology advances and should remain confined to extraordinary situations."
The 25-year-old suspect was killed after he told hostage negotiators that he was angry about recent shootings of black men by police and that he wanted to kill white people, especially police officers.
Police spent hours negotiating with Johnson, who indicated there were possible explosives inside the building, before using a police robot to detonate an explosive, killing him.
"We saw no other option but to use our bomb robot," said Dallas Police Chief David Brown Friday morning. "Other options would have exposed the officers to grave danger."
Johnson had "plenty of options to give himself up peacefully," said Dallas Mayor Mike Rawlings Friday afternoon. "He had a choice to come out and we would not harm him, or stay in and we would. He picked the latter."
The robot used is manned by a trained police officer, Klinger said. The device contains an arm that's essentially an extension handle, which police can use to carry anything from a bomb, camera, encrypted phone, distraction devices or even food to engage with the suspect.
For the past five years, one particular police robot manufacturer by RoboteX has been passed around at police special tactics conferences, said Rob McCarthy, the former senior supervisor and assistant commander of the LAPD SWAT team. They are small track vehicles, about 18 inches tall and a foot wide, weigh about 12 pounds and can go up to down stairs.
Dallas police used a C-4 model to detonate the bomb.
The RoboteX model is being used in more than 800 police departments all over the country, said the company's president, Eric Ivers. McCarthy described the Dallas SWAT team as having "very progressive training."
"It doesn't surprise me that they have this ability," he said. "[The robot] takes away some of the danger to deliver something that would be considered critical, in this case an explosive device."
The RoboteX devices cost anywhere from $20,000 to $70,000, depending on how they're equipped, Ivers said. RoboteX is considered a lower-priced model, her added, with higher-end versions costing upwards in the hundreds of thousands.
Klinger, McCarthy and Ivers all said this is the first instance they're aware of where a police robot was used to kill a suspect. The method has been practiced but never actually implemented on the field, a source with the ATF told ABC News. Before the Dallas ambush, they were used predominantly to disrupt improvised or explosive devices, or IEDs, Ivers said.
Police typically train with the devices for two full weeks initially, with the individual departments providing continual training, Ivers said. RoboteX offers consultations to officers when necessary.