The character of Buckley is based on the 1931 murder of Adolph Ruth, whose knowledge of the Lost Dutchman came from his father through an employee of the Peralta family. He disappeared in Superstition in 1931 and his skull was found half a year later with two bullet holes in it. Also discovered was his unfired pistol and his checkbook in which he had written that he had indeed located the mine. Over the years other murders and disappearances of treasure seekers have helped to build the legend.
The real Jacob Walz, who claimed that he had discovered the Dutchman, died of pneumonia after severe flooding on his Arizona Ranch in 1891. He was nursed by Julia Thomas, the same name as the character portrayed by Ida Lupino and reputed to have been a quadroon. She claimed Walz had told her the mine's location on his deathbed and even sold shares in a Lost Dutchman mining company, but nothing ever came of it.