Steven Baker explains how he stumbled across this lead while doing a separate investigation into CHP clearly using non lethal weapons on the crowd against regulations.
Those crowd control weapons are explicitly NOT to be aimed above the waist, yet they were. He also reports that the CHP officers implicated who train others with these weapons often say in their training classes "oh by the way, if you want to START a riot, shoot them in the head ..."
Finally we have long known the suspect stands 5'7", so not exactly a needle in a haystack as Finding is desperate to imply.