I keep going back to the original facts. He went to work. His phone was pinged. He was at Arrow Scrap. His car was at the train station.
Taking out all of the other stuff - what happened to Robert???
Somebody did something with him or he did something with himself. The fact that there is no evidence of a crime, leads one to believe that he did something to himself. But, why? There would have to be a motive (on his part or somebody else's part).
And, he did a "minimal" transaction at Arrow Scrap. He didn't have his ID and I believe, without ID the transaction has to be less than $50.00. However, since he was a somewhat regular customer, they could have done a larger transaction. But, sticking with policy, he had to go to Arrow Scrap for $50.00 - what would be the point of that on such a busy weekend???