Complex sentence: Cedar Jack, who lived about forty miles out of town made a living cutting cedar fence posts, gave Curtis opportunity to observe him when Jack would come to Las Animas, where he would usually end up drunk and in jail.
Split into simpler sentences: Cedar Jack, who lived about forty miles out of town, made a living cutting cedar fence posts. Curtis observed him many times Jack would come to Las Animas, where he would usually end up drunk and in jail.