Vigilatism.....
Could he have gotten away with shooting the Russian guy in the field?
I guess everybody involved understood the implications of his actions, but isn't a cop's role to just tell him to "Stop and drop his weapon" and then take him to police headquarters?
In real life, if he went into the field, the cops would have ordered him to cease what he was doing (not merely yell out his name like a mother ordering her kids to be still) and follow procedure.
Noway he would have gotten away with that. The system works....