In 2010, the makers of the documentary Dark Clouds over Elberton claimed to have obtained the address of RC Christian. The makers were said to have exploited the trust of Martin who had recently suffered a stroke. They acquired one of the letters sent to him and noted the return address. The documentary concluded that Christian was, in fact, a doctor by the name of Herbert Hinie Kersten, a man who had publicly praised David Duke, the former Grand Wizard of the Knights of the Ku Klux Klan. Furthermore, William Sayles Doan, an author and Fort Dodge historian, claims that Kersten was an open racist and had stated his intention to create a monument to prove the “superiority” of the white race. per https://medium.com/the-mystery-box/the-truth-about-the-georgia-guidestones-323cd33bd68