Over here in the USA, police aren't given permission to execute people.<quoted text>
That's right, so what if the thug was smashing the cops face
We have here in the USA courts and people guilty of a crime are given punishment by judges, not by police.
You don't know what happened.
What I do know is: police are obligated to show restraint and fire only as a last resort if their life is threatened. If this were the case here, then it will come out in the investigation that is not complete. Many eyewitnesses have him standing some distance away from the police officer with his hands over his head and surrendering.