If he was coming back at the officer, six shots makes some sense. Cops are trained to shoot until the threat is down. Only one or two of those shots would have stopped someone from coming at them. I can’t condemn solely on that.
I give cops a lot of leeway about number of shots and placement. I shoot USPSA and the only pressure I have is time and trying to beat my score. I don’t have anyone trying to harm me. Shooting quickly and accurately is difficult. I’ve seen Master class shooters completely bone a stage and miss targets or hit ‘no-shoots’. Contrary to popular belief, most cops really aren’t “gun guys”. Many don’t shoot their gun except for the minimum training and re-qualification.
It is also surprising how fast people can close in on you and cause harm. Do a search on youtube for something like the 21 foot rule. Basically within 21 feet the average person can close distance and strike or stab you before you get your gun out. I’ve also see training video where people do things like shoot and turn. When the cop finally fires the assailant has his back turned to the officer - making it look like he just shot a guy callously in the back, when he was responding to a threat as fast as humanly possible.
Now - the point of all that wasn’t to defend the cop in this situation, but to point out that after the fact evidence doesn’t always conclusively prove what happened. I hope that with the FBI involved they do a thorough investigation, and if this cop went all vigilante that they put him away.
Also important to note - even if this cop acts were justifiable, I think there are a lot more examples out there where cops use of force is questionable to out right unjustified.