After reading the several facts about the case and many theories propositioned by various people, I recited what I knew about the case to my son - an ex military. He said, "Have you ever seen "No Country for Old Men?", the tracking device was in the duffle bag".
Blair's green duffle bag was apparently the only thing missing from the crime scene. If I were the police and I wanted to solve this cold case, I would investigate as to where that duffle bag came from and who had access to it before he left Canada. That will lead them to the killer.
Knowing this, the entire story makes sense to me.
This is an interesting angle I have never been creative enough to think of.
This could add credence to one of the possible theories I have.
I have at least two theories about this case (thought certainly not sold on either)
1) He had something that someone wanted back. This was 1996, so it is unlikely that it was a USB, electronic, etc. I think that the money was withdrawn by him as an offering to the people who wanted the item back.
I particularly think it involved a woman...I think that the item may have been a ring, a necklace, maybe even ultrasound picture.
Blair may have took everything he owned to them, hoping they would accept it instead of taking the possession he so highly cherished. I think this is why there are indications that he was searched, to the point of having his anal cavity searched as opposed to being sexually assaulted.
Where the "No Country for Old Men" tracking device comes in involves the car key. (I think it is a little farfetched, for with the technology at this time I think they would have had to be very closed to Blair to sound off the tracking alarm) I think that Blair intentionally acted like he could not get back into his car, and the the gas station he was at was in very clear view of the construction site that he died at. This site may have been were his former coworkers and now enemies where working. I think that Blair used the car to hide the item that he wanted to keep, hoping that the people who wanted it back would accept his money instead.
Blair was then beaten and strip searched for the item, possibly being thrown out of the car and then ran over (not necessarily in that order)
2) It was an accident involving someone with a medical background.
In this theory, I picture someone like a former or current military medic or EMT. This person hits Blair with their car by accident. They rest Blair's head on his shoe for support, and begin to remove his clothes in effort to see if there is bruising, protruding bones, etc.
This person may have not been in the position to draw this kind of attention to themselves for a variety of reasons. Perhaps they were driving drunk, maybe they just felt like they could not afford the negative attention.
These are just two theories, not ones I am sold on being the ultimate truth, but kicking around ideas.