Here is the theme of the song (from wiki)
The story is told from the point of view of a young man who takes his brother’s rifle out onto the hill one morning. As a rider crosses the plain, the singer takes aim (“I drew a bead on him; to practice my aim.”) The rifle goes off in his hands, killing the rider.
The man runs to the salt lands, throwing the rifle into a stream. (The Cash cover changes “salt lands” to “south lands”, and “stream” to “sheen”. Sting supposed the latter was due to a misprint in the lyrics Cash was using.) He is discovered by a sheriff, and is struck by the realization of what he has done.
He is brought before a judge and jury, where he begs forgiveness and wishes he was dead. Awaiting execution on the gallows, he sees as a “trick of the brain” the rider return, so that they will ride together “till kingdom come”. The man prays to God for mercy.
I made this sketch after listening to the song not much in detail, so there is an error it, I should have put the gallows on the hill and placed that fellow in the plain… anyway, this is one of my favorite country song.
This is my favorite version