First of all great topic.
Sig guy is correct, Furtive movement is the legal term that would cover this scenario.
"A furtive movement in such cases is a movement reasonably consistent with going for a weapon and not reasonably consistent with anything else under the circumstances.
"The law does not demand that your perceived antagonist have a real weapon in order for you to employ lethal force in self defense. It only demands that his actions create in your mind a reasonable and prudent belief that he has a weapon. If he is close enough to employ such a weapon, and if his actions are consistent with an armed person trying to kill you (Diallo turned suddenly and thrust the hand with the black object toward the officers), then the requirements have been met for you to justifiably use deadly force in order to defend your own life."
Now the issues begin. I would call the police and have them respond. I assure you if he does not call right then he will call later after talking to friends and family and report you as the crazed gunman in the parking lot. If the other person does not want to stick around great better for me. Get a description and LPN is possible.
Now a couple of things to consider. The experience, attitude and training of the officer is going to play a big part in this. Do not come off with some macho "I was 1/4 pounds worth of trigger pull away from busting a cap in him, but my Navy SEAL, Ranger, Security Guard training saved him" attitude. This is the time to articulate what happened in a calm manner relating the facts and nothing more. You perceived a threat and reacted to it. You did not use deadly force as no weapon was visible or presented.
This is also a time that if the officer feels the need to disarm you let him without promoting the 2nd amendment, your right to carry or the legalities of disarming you. For those of you that carry audio, video or a stenographer with you for encounters with the corrupt, death dealing, drug smuggling, evidence planting LEO's I would not announce that fact unless required by law it could just make matters worse. If the other person stays do not engage in a ******* contest of who did what to who let him say his piece and you say yours.
1911PKR just wanted to point out your statement about your lawyer pointing out the bad guys previous crimes. It won't happen. Prior bad acts, arrests or convictions, are deemed prejudicial in the legal system. As far as anyone is concerned the guy was returning from church where he fed the homeless hamsters of the world while knitting sweaters for the elderly when you drew your weapon and threatened him.