Looks like the cop was angered by his suspects resistance and/or verbal incitement, and vented on him. It looks like second degree murder is the appropriate charge, and it might get downgraded to manslaughter if they buy that he was following Department escalation procedures, and then wrongfully opened fire due to excessive passion from a struggle.
They were away from the vehicle in the traffic stop, indicating that the suspect walked away from the vehicle and was being non-compliant. It must have gone on for some time, for the incident to draw spectators to film it - probably some shouting, possibly some scuffling.
If the suspect assaulted the officer prior to the video starting, he may have been fleeing a felony, which puts the shooting on a different legal footing.
There are escalation procedures for subduing a suspect, e.g first give a command, second attempt to physically compel compliance or apply a restraint (handcuff), third might be non-lethal incapacitation like pepper spray or stun gun, and finally the use of lethal force.
After the stun gun was deployed, the gun was the next and last escalation step. Clearly, the cop was not in danger when the suspect was running away, so self defense will not fly to justify the shooting. If he was legally authorized to shoot to stop a fleeing felon, he might beat the murder wrap on that basis.
It is pretty clear that he tampered with the evidence, planting the stun gun near the suspect (a time-honored technique - many cops used to carry a small back up gun available to plant on anyone they might shoot). He might have also (likely) made false official statements which could get him fired, and possibly another criminal charge. The fact that he has already been fired, indicate to me that he did lie.
In this case, I think that the officer is likely to go to jail for a long time. Many sentences are tripled on law enforcement personnel who are found to have violated their trust.
This is clearly a much more serious incident than Ferguson, which was a complete fraud against an innocent police officer, or the Staten Island incident Eric Garner, where a suspect resisting arrest died from a heart attack and positional asphyxiation while normally restrained, due to his obesity.
I agree, use of force policies are strict for a reason, and they are talking about the death penalty for this guy, first I have ever heard about a cop that might be sentenced with that.
That's what I'm seeing too. The taser is laying on the ground, possible struggle for that, and when the vic sees the cop go for the gun, he runs.
Amazing. At .24 on the video, the cop after shooting, looks directly at the guy shooting the video, clearly sees him.