If that were Kiely and her car at Boca at 11:00 Saturday morning with an unknown male, why would she or he drive back to Prosser when, by this time, people were already looking for her?
The only possible hypothesis I can come up with is that KR and this unknown male drove to Boca to drink, smoke, canoodle, etc. after the party. They fell asleep in the car and something caused the battery to die, maybe listening to the radio on accessory mode?
After the tow truck driver gave them a jump:
They drove back to Prosser where the male had left his car?
Kiely then somehow drove into the lake?
They drove back to Prosser, something happened, and they both went into the lake, the male escaped and Kiely didn’t.
Big problem with this theory: The lake was busy Saturday morning with boaters and fisherman and people looking for Kiely. Why wouldn’t someone have seen something?