Oh no!
The odd circumstances include vanishing while in the process of moving (to me, going to the trouble to move could mean he was in danger, but probably not - and not likely he was suicidal, it’s too exhausting to live let alone pack boxes and move!), and his dog being found in the car while his body was found outside the car.
I think Boo Bear (his dog) might be a key. Unless Levin took him/her all that way and killed him (no doubt mercifully via gunshot/asphyxiation...well, more mercifully than locking in a car and leaving behind), Levin probably had to pull over and get out for some reason, and something unexpected happened to him then. Probably a health incident because who would follow him all the way out there, get him to pull over, etc.?!
Weird. Sad.
"We've had threads about guys fucking picnic tables, animals and dead bodies. Third boob ain't going to stop a damn thing." - cleanskull