I believe JM could be connected to Alexis Murphy's disappearance, despite the press release from the Commonwealths Attorney for Nelson County claiming that no evidence "at this time" exists.
RT could have identified the wrong guy, because he was grasping for straws. Perhaps someone loosely similar in appearance to DB was with RT that night, and he felt that he needed to give LE a name. Perhaps RT did not care that he identified the wrong person (DB). Perhaps he even knew.
The orange car near Alexis Murphy (in that picture at the gas station) does NOT look like a sign to me. It looks like JM's car, and THAT looms too big of a coincidence in my mind.
It really depends upon perspective. I know a man who weighs nearly 400 pounds, not everyone does. I might describe JM as a man of medium size, just because he seems so much smaller than a 400 lb. man.