Cops say that the 59-year-old murdered his pal Joe Daggett because he was hopelessly in love with his wife.
Cops believe that in March 1988, Saul disposed of his pal, whose body has never been found, before leaving his car in Midland International Airport car park.
The whereabouts of Daggett still remain a mystery, but he is presumed dead.
Since the rancher's disappearance more than two decades ago, the Texas Rangers and local law enforcement doggedly pursued the case and ultimately tied Saul to Daggett's murder.
Saul was taken into custody by New Mexico State Police as a fugitive from justice and will now serve the rest of his life behind bars after being sentenced to 60-years behind bars.
Two other suspects have also been tied to Daggett’s disappearance, George McIntyre and Robert Ezell, have also been indicted for conspiracy to commit capital murder.