So, the two dozen cops trying to apprehend Rodney King saw themselves as having not much alternative to bouncing truncheons off Rodney until he decided to come quietly. (Plus, they'd been chasing him at 100 mph, so whomping him just seemed like a good idea at the time.)
P.S. Commenter gwern found an article from the LA Times, not the NY Times as I recalled. (I was a subscriber to the NY Times in Chicago at the time, but I was vacationing at my parents' house in LA at the time of the verdict in the second trial.)
> Jurors also played and replayed the best evidence in the case--the videotape of the beating that had been taken by an amateur and enhanced by the FBI.
> "We went through it frame by frame, slow-motion, fast-motion, God I don't know how many times we watched that thing," Juror No. 9 said.
> The tape, made by a bystander, could not answer all their questions. It was blurry at one crucial moment after King was struck and fell to the ground. Some jurors said they could see Powell using his baton to bash the fallen King in the head. But others had difficulty seeing head blows, even when the tape was viewed frame by frame.
> All could see a powerful blow that Powell later landed across King's chest. King was on the ground at the time, on his back.
> "That chest blow was unreasonable and we felt it was not to effect an arrest but just to hurt the guy," No. 9 said. "That convinced about a third of us."
> Powell's laughter while making a radio call to request an ambulance for King also contributed to jurors' impressions that he had acted callously. But the panel stopped short of taking a vote.
So, to the extent that this is the article I remembered, it doesn't say that it was the last blow that led to the conviction, just that there was one blow that was seen by a significant fraction of the jury as unjustified beyond a reasonable doubt. But, in any case, that's awfully different from The Narrative.