I'm not 100% convinced, but I'm still leaning towards GS never returning home that day. I think RD's additional video footage before 10am and after 2pm probably paint a clearer picture of what actually happened.
Did she load anything in the truck? A board? A suitcase?
After returning home, did she unload anything from the truck? I know the bed of the truck was mostly off-camera. Did she back the truck into the garage? Did she leave the house again before calling LE?
The problem I've been having with the "he never came home" theory is that the tuesday night trip in the tiguan, to the assumed dump site, wasn't making sense to me. Why would she make that trip if his body was already there? It's not like his bedding etc. was found there. I guess she could have dumped the bedding away from his body, up in that general area, but I would think that she wouldn't want the bedding to be anywhere near him. (I guess unless eguardo had taken the bedding with him).
I have come up with a theory that I think makes sense, but I kind of feel like I am cheating because I am kind of working backwards from my belief that she removed his body from the area on friday with the rented nissan.
This is all speculation. I'm going to try to stick to a single narrative, and try to not list every possibility that I can think of about each fact of the case. This is primarily to explain the tuesday night trip to the dump site (assuming his body was already there). So here goes:
So sometime before 10am on monday, she attacks him in his bedroom. She bandages him up, and they leave in the truck. She kills him, and dumps his body where the particle board was found. The particle board was in the bed of the truck, and she covers his body with the board in an attempt to hide him. She goes home, cleans, and puts the bedding etc. in the back of the tiguan.
Tuesday afternoon: she realizes that LE is on to her. Right after they ask for GS's toothbrush, she starts freaking out. She immediately googles "volkswagen car net." Did they find her car? Did they find the body?
A few hours later she goes to the airport to see if the tiguan is still there. She brings the suitcase from home, and puts it in the tiguan (if the suitcase wasn't in the truck on monday). (The suitcase bothers me about how and when he was put in it. I kind of feel like I am reaching here. I guess she could have brought the suitcase with her on friday night in the nissan as well.) Also, the tiguan has the bedding in it that she needs to get rid of. She leaves the airport in the tiguan around 7pm. She was alledgedly in the dump site area from 8:30 until 10:20. Say it takes 30min to get from airport to dump site. Where was she for the other hour? My guess is that she dumped the bedding somewhere first. And why was she in the area for nearly 2hrs? She only stopped at the assumed dump site for about 5min. My guess is that she was lost, or couldn't remember/find where she had left him. (For arguments sake, I guess she could have just as easily just have been searching for a spot to dump his body as well).
She finally finds the spot around 9:15, or 9:30, or something. Goes to check that he is still there. Maybe drops off the suitcase? Puts him in the suitcase and leaves him there?
I guess that's all I have to say about that.
Sadly, I think maybe my only idea in all of this that I like is her using the particle board to hide his body.
JMO
P.S. All of you insomniacs can thank me later.