The officer who killed Philando Castile, whose death was streamed online via Facebook Live, took a class that advocates using lethal force at any sign of possible danger.

The seminar is called "Bulletproof Warrior," and it highlights situations where police have been killed on the job, according to the Star-Tribune. As a preventive measure, the class advises officers to shoot someone who may pose a threat before they get a chance to shoot first.

“Every time a video came up where the officer hesitated, (the instructor) would stop and he would say, ‘This is a point where there should have been a reaction, he should have engaged,’” William Czech, a civilian who went to the class to learn about policing tactics, told the Star-Tribune.

The course is offered by Illinois-based Calibre Press, which promises to develop “smarter, safer, more successful law enforcement officers” on its website. Officers from around the nation have received this training. Its Facebook page shares stories about how people "wrongly" assume policing is racially biased and don't think police lives matter.

Yanez took the course in 2014, and the language used by instructors appears to portray citizens as enemies of police officers. Suspects are sometimes referred to as "predators" or "adversaries," according to US Uncut.

“Police training became very militaristic and it caused a lot of the problems that are going on in the nation,” Michael Becar, executive director of the International Association of Directors of Law Enforcement Standards and Training, told the Star-Tribune.

Besides showing videos of police shootings, The Star-Tribune reports that the seminar also cites verses from the Bible that may imply not all killing is unjustified, and it reinforces the idea that being a police officer is an extremely dangerous job, despite studies having shown that being a police officer is a lot safer today than it has been in decades past.

Ironically, Castile had actually taken a state-mandated firearm training in Minnesota that advocates being cautious during traffic stops and showing respect to police officers.

Philando Castile was killed after being stopped for a broken tail light. He allegedly told the officer he had a concealed carry permit and that there was a gun in the car. His death gained national attention partly because his girlfriend, Diamond Reynolds, live-streamed the aftermath of the shooting on Facebook. Reynolds claims in the video that he was shot while he was reaching for his wallet. Castile had been pulled over 52 times since 2002, which family members have alleged was a product of racial profiling.

Calibre Press was not able to comment before this article was published.