I am a bit behind since late last night so sorry if this has been posted (I will go back to catch up, but also want to be current!). And I offer this idea with a wink in my eye because the odds are highly unlikely... But...
What if KR and her car were dumped into Prosser Reservoir (down that dirt / beach stretch) AFTER LE had finished their grid-type search of the reservoir... meaning, what if in the dead of night late last week someone moved KR's car?
I don't think that could be possible, there have been search teams and campers,boaters, people paddling etc and I'm sure LE would be keeping some kind of an eye on the area one way or another. JMO