It seems that in the recent dev-branch update the changes have been made to this but they are not optimal.
If you will fire and kill a soldier from behind bushes enemy AI will not react in any reasonable way apart from going into danger mode and facing into a wrong direction. However consecutive shots (not even killshots or hits) will produce the same behavior with them instantly zeroing on your exact position
However if you will launch a repro and move a few meters sideways so bushes won't conceal you and do a killshot in the open - enemies will instantly know your position as typical for the issue. Even when facing away.
Please test this further with repro and the most recent DEV update to confirm.
Expected behavior:
It shouldn't matter to AI if you kill his mate or just fire randomly into the sky. When hearing a shot, be it a killing shot or any shot AI should turn into its approximate direction. After that AI should use nothing but its own AI eyes to find you. Of course the consecutive shots should turn that approximate direction into the exact direction eventually (+/- a few shots to add believable randomness a la human behavior) and reveal enemy's position if AI is facing the enemy but still can't find him to not make AI harmless to well hidden enemies (since even a human player will eventually spot kicked up dust from the gun fire) - the latter one of course requires some balancing to not make AI cheaty.