It just occurred to me that maybe he didn't know she was dead.
This whole time, I've been thinking how he had created perfect cover by taking off and solo hiking and then hitch hiking back, and it has never made sense to me that he didn't just continue with that plan...even if she wasn't discovered by the time he returned. He already had witnesses that he wasn't there so he could easily say he just found her that way. He had PROOF that he'd left the campsite and then returned, so he certainly had thrown more than a shadow of a doubt in there about his responsibility for her death.
I theorized once that SOME of his actions made more sense in the context of his innocence. However, I hadn't considered another scenario that sort of fills those gaps for me. Of course, this is all MOO:
- They get into a fight on the 27th. (We have evidence this was likely based on the Merry Piglets incident)
- He grabs her and strangles her (We also have evidence that he, at the least, "grabbed her face" in the past, so this might have been a typical response for him)
- He, thinking she is unconscious, leaves on a solo hike to "cool off" (His impulse after fights was to separate himself from her in some way as evidenced by Moab, CL's comments, even Rose).
- After a few days, he cools down. Maybe he considers flying home, and then changes his mind and decides to return to GP (Based on the odd convo he had while hitchhiking, and he seemed to relay that she was back at the van working on her social media, possibly he really thought this to be the case.)
- If he took her phone with him, left his own phone or had no way to charge it, if cell service was spotty, or he assumed she was mad and ignoring him, he wouldn't be able to have phone contact with her anyway, so he wouldn't have any other possibility for attempting to contact her until he returned to the van.
- Upon his return, he either doesn't find her and hangs out for a little bit waiting for her and then leaves, or, he does find her, realizes he's responsible and panics.
In either case, it all makes more sense this way. IF he didn't find her, he thinks she's left and so he takes off for home with the van. He thinks the Petito's are calling because they are angry. He lawyers up because he's expecting DV charges. Eventually, he realizes that she's actually missing and considers his own culpability...leading to his trip to the reserve.
If he did find her, then he takes off for home in the van in the same way because he realizes he has killed her and panics. That makes more sense than the idea that he killed her and then laid out what could have been a perfect alibi and then just scrapped it out of the blue and took the van. He could easily relay to his parents a story about how they got into a fight...she's angry with him...he could get DV charges...etc. He had time to think about that story on his drive back to North Port, so it would have been laid out well by the time he got there.
The Laundrie's might have felt it was possible that GP was setting him up to catch a false DV charge based on whatever story he told them. If they then wished to protect him from such charges, it would explain almost all of their actions, or seeming lack thereof. If you consider the characterization of the Moab stop, where GP was considered the aggressor, this makes even more sense. By the time RL and ChL realize that something more sinister has occurred, he is already "missing".