Just another bungling of the investigation IMO. It's almost as if they were not really looking to investigate. They had made up their minds regarding what they thought and didn't want to tick off superiors, IMO. I can't think of any other reason for skipping so many investigative steps. Filming and plotting are so important, especially when investigating.
Also, KR should not have been driving that night (obvious to us all), but probably most of the party goers were in the same predicament. If KR was blacking out at all, then it would make perfect sense to me that she may wonder if she had possibly hit JOK with her backing vehicle, if she remembers backing up. On the other hand, the wounds suffered by JOK do not represent being hit by a vehicle IMO, as well as the scratches on his arm.
I'd hate to see an innocent go to jail. On the other hand, I'd hate to see a murderer get away with murder. Has there been a history of domestic abuse by KR? I just can't imagine anyone deliberately killing anyone else though we see it all the time here. I picture an accident at the very most in the case. So I don't get the murder charge. But we'll see as the trial continues.