Arnold Otto Krug was born in 1896 in Forest, Wisconsin, the second youngest of ten children. Krug worked as an auto mechanic in Milwaukee until he went to Arizona to follow his passion for painting. A disciplined artist, he would go into the desert at the same time every day to paint. A favorite subject was the Superstition Range east of Phoenix.
At one time he was engaged to a girl from Milwaukee, but the relationship ended when he moved to Arizona. At various times from 1927 to 1942 he lived in Arizona and California. He never married.
Arnold died in May, 1942 in Phoenix from bronchial pneumonia. He is buried at the Rienzi cemetery in Fond Du Lac, Wisconsin.