1). Look at the “subject’s” appearance. At the Trolley Square Mall shooting..... The police were on scene BEFORE the fight was over, and had to evaluate the off-duty cop before linking up with him; His physical movements, weapons handling, use of cover and clean cut hair cut sent a strong message to the first uniform on scene that this might not be the bad guy. Does the subject of your attention look like he is trained? Does he dress and look like a “good guy”. Certainly not all good guys look the part, and that is why we have additional points of reference.
2). Look at what is he armed with? Is it a modern high quality weapon, or is it some cheap firearm. The police would not use a Tech 9, nor an SKS, nor even a shiny revolver today. Black modern pistols and black modern rifles are quite common however. There is even an agency issuing Arsenal AKs in 5.56!
3). Look at his actions. Obviously, if they point guns at you, or begin to, all bets are off and you stop them from doing that. But that will not always be the case. In video of the Mumbai murders, the terrorists were very relaxed. They were not worried about being shot and were doing all the shooting themselves. Contrast that with the movements of the victims and Indian police responders, who were running and making use of cover. In other mass shooting events, the bad guys were described as moving casually with their weapons.
One member at my forum relates how the Israelis found it relatively easy to determine bad guy from good guy with only a few seconds of observation based on actions.
He writes: "In the words of one army responder: ‘There were armed people shooting at women and children, and there were armed people who were not. I shot those in the first group. No civilian responder was the victim of friendly fire, despite the fact that none of us knew each other and none of us was in uniform.’ "
If you choose to get involved in an incident as CCW Operator, or Off Duty Officer, or if you are sent as a Uniformed Officer to a call involving gunfire, consider these three elements before making your deadly force decision. If you have time to analyze what is going on, you also have time to evaluate what you see before you. Everyone wants to shoot the bad guy, but nobody wants to shoot a good guy.