Like I said before, I feel the partner did his job in this one. He assumed his partner was shot [hearing a shot and seeing his partner go down] its a pretty basic assumption. Youve already got raised alertness with the fact a man flees, hes driving reckless, they had no idea why this man ran. Like I said before, your basic assumption is drugs, alcohol, guns, or a felony warrant on this man.
You approach with caution, i.e hand on weapon, you hear the shots, [you draw your weapon] see your partner go down, [the hard part is to determine if he was shot, or if it was a misfire (i guess?)] He made the call, and presumably felt his life or the life of his partner was in danger and open fired.
I applaud this man, yes the BG was killed when it didnt need to happen, but thats the life with a LEO you make some mistakes, and this one may have caused him his job, or at the most, some jail time.
Either way, I say he made the right call, he had no idea what had happened. If anything, as soon as his partner fell and accidentally discharged his weapon, he should have been on the radio letting the others know what happened.
Only two defining forces have ever offered to die for you, Jesus Christ and the American Soldier....One died for your soul; the other for your freedom.