There's this amazing thing called the human body and there are many places on it where a person may be shot that'd inflict enough pain to neutralize them without inflicting a fatal wound. A competent, well-trained police officer would've been easily capable of making such a shot at that range without endangering himself either.
No police in the US are trained this way. They are trained to use their weapon to stop the threat, and that (usually) means 2 shots, center mass. And the science* backs it up. Hitting someone jacked up on adrenaline (and Og knows what else) with a sidearm in an extremity is:
a.hard to do
2.even if it works, likely won't stop the threat right away
C.increases likely hood of ricochets
Two shots, center mass stops the threat, right now.
Yes, there have been a few police sniper shots, but in more static environments, not in this type of situation. Even two shots, center mass doesn't always work, but it usually does. Often the person dies, but that's secondary to stopping the threat.
*it seems it's not settled I guess....some people seem to be suggesting that three shots center mass is even more efficient and others going so far as to say two center mass and one to the melon...but that seems a bit too "cowboy" for me, and harder to do of course.