The old man seemed to have had no enemies but his sons.

His sons?
The thought of Jeff suddenly sprang into my mind.

If anyone on earth owed the Colonel a grudge it was his elder son.

And Jeff had more than his share of the Gaylord spirit which could not lightly forgive an injury.

Could he have returned secretly to the neighborhood, and, following his father into the cave, have quarreled with him?
Heaven knows he had cause enough! He may, in his anger, have struck the old man without knowing what he was doing, and overcome with horror at the result, have left him and fled.
I was almost as reluctant to believe him guilty of the crime as to believe it of Radnor, but the thought having once come, would not be dismissed.