I only heard of Marshall's case a few days ago, so bear with me if I have some incomplete or incorrect information, but I wanted to offer a few thoughts as someone brand new to the case.
1. Suicide ? That just seems a ridiculous conclusion to me for a number of reasons. You don't have to drive 14 hours away, deep into the wilderness, to commit suicide. You don't need to torch your truck, walk away taking your cell phone, backpack and contact lenses with you just to commit suicide. And you certainly don't need to remove the steering column of your truck before doing any of that.
2. I don't know the facts of this case very well, but I will say that my very first thoughts regarding his apparent desperation to get into the storage unit, and the fact that once he did get in he spent 2 hours in the unit, were that he was retrieving drugs to resell. If he was cutting the drugs or packaging them, that 2 hours in the unit sure would make sense. Just my first thoughts.
3. Steering columns don't just disappear into thin air...so where is it ? Let's say that Marshall did commit suicide ? Why would he carry the steering column off with him ? Let's say he just wanted to disappear and start a new life. How does carrying away a steering column help him do that ?
4. It's possible that the truck arson, steering column theft, and Marshall's disappearance are 2 separate things, I suppose. He could have simply taken his backpack, phone and contact lenses and walked away from his truck. And someone could have stumbled across the truck, stolen the steering column (which you can sell on the black market for around $800, I think ) and then torched the truck. It is odd that his truck was torched, but his belongings were removed from the truck before it was torched. The photos certainly look like someone had gone through his stuff. But this is a very remote area. Hard to believe that someone just stumbled upon an abandoned vehicle in this location.
5. Did they ever find Marshall's car keys ? And is there ANY evidence that Marshall himself was ever at this location ? Because it almost sounds to me as if this vehicle was stolen and brought to this location. I'd be interested to know if the steering column on Marshall's truck was equipped with an anti-theft device.
Just some random thoughts.