First question, can we pin down when he was in different locations and the times he was there? In other words, let's separate what's known from what's suspected. One thing that comes to mind is that he stole a truck and wanted to do something, perhaps just get out of the area for a while, perhaps to commit a crime (like moving drugs for a someone or a gang), perhaps he had a psychological issue, or something along these lines. Another idea is that he wanted to commit suicide but didn't want his family to know, due to shame or some other issue. How do we know he was connected to the stripped truck? Who put forth that claim in the first place? It sounds like another possibility is that a "friend" (perhaps some sort of "partner in crime") made up the story after doing something to Nieko, and Nieko never left the area around Jasper. All this is related only to what you stated in your post.