Maybe charging 1st. Degree Murder is a way of getting a plea bargain or getting the perp to plead to 2nd degree murder.
The cop was trigger happy.
More likely an attempt to head off civil unrest and political reprecussions. They’ve had it for a year, and they decide to overcharge within a day or two of the dashcam tapes release, I don’t buy it. Though the shooting appears to be problematical in the video, I don’t buy 1st degree murder, and if there aren’t lesser charges filed, they’re asking for an acquittal. Of course none of this know what other evidence there is, but it’s reasonable to assume if it was compelling, charges would have been brought long ago.