Chances seem pretty good that Ruth found the LDM. Trouble was, no one was watching at the time. Once the killers decided to murder him for his "map", they returned a day or so late and mugged the old man.
They looked at the map, and realized they had no clue where it lead to.
Ruth, knowing he is a dead man, and being a tough old bird, decides to lead them away from the mine.
Once they realize he is not taking them to any mine, they kill him. His body lies where it fell. When Barkley goes looking for him, he tracks the horses with ease, finds the body and suspects that the mine may be near-by.
Barkley decides, no harm...no foul, and moves the body away from the suspected area of the LDM. He was, after all, interested. Not realizing that Ruth had a silver plate in his hip, he seperates the head from the body to make identification of the corpse more difficult, in case it is found.
On the other hand...maybe Ruth was in the wrong place at the wrong time. Lot's of unexplained deaths in the Supes.

Joe Ribaudo