I know this is far fetched and all, but where was the dog found? In the house? I know their dog has gotten away before. Is it possible she had been out searching for the lost dog and something happened to her during that time? I know, a stretch, just wondering.
ETA-I know the couple were divorcing, but is it at all possible that she may have been meeting someone at that location secretly? And then decided to hop in their car and return back later to retrieve her car? What was the situation with the divorce? Who and why were they divorcing this time around and why were they both still at the home? Were they at a stalemate as to who needed to leave? Or were they both seemingly happy about staying in the home for the sake of the kids? Had KS been going out with her friends a lot lately or with someone else? I know plenty of women who are in a divorce situation who do that (as well as men.) Kind of getting used to the idea of freedom again? The family seemed convinced that the couple loved each other very much, yet they were divorcing. I know of plenty of people who have amicably divorced like this, but it certainly isn't the norm, at least not enough to just disregard the fact when one of them goes missing.
