William MacLeod Raine 
Bucky O’Connor: A Tale of the Unfenced Border [PDF ebook] 

A long standing mystery is solved along with some unusual plans concerning how to free an innocent man from prison. Strong allegiances on both sides of the law.
The author included some historical details and demonstrated a good working knowledge of the people, area, customs, and activity of the times in which the novel is set. His story line is believable and informative of the Southwest in the early 1900's.