The more I sat and thought about this case, the more off some things seemed. If he left voluntarily, was that a very spur of the moment decision? It seems if that is the case, it would almost have to be last minute, otherwise, why bother getting in the vehicle with your boss & the crew to begin with? Why not just go missing from whatever location he was picked up from prior to being picked up?
He was accidentally left behind? Is that just the story the crew is going with to support his going missing voluntarily? I would think the leader of that crew would be in trouble for leaving a man behind "accidentally" and wouldn't want to risk his job or get in trouble with superiors just to cover for a crew member wanting to run off.
If he is the most senior person, his job wouldn't be on the line, but who would want to deal with police asking you questions about the guy you "accidentally" left behind? Surely he would have considered that being likely.
The whole situation is odd. What really happened out there?
I thought of a scenario where perhaps he was left behind, understandably upset by it and thought "no way in heck am I EVER working for this guy or with this crew!" and decided there he wouldn't try to get to the worksite himself to meet back up or attempt to contact them, but it wouldn't make sense for him to not contact his family either by now. So I guess that's unlikely.
Are we sure there wasn't an argument or misunderstanding of some sort during the drive and he was purposely left....or worse and the "accidentally left" is just a story?
Maybe even an innocent "let's leave him" prank/joke between work guys that went awry when they couldn't relocate him?
How long has he worked for that company/that lead/with that crew?