Billionaire industrialist David Koch, a driving force behind conglomerate Koch Industries who as one of the world¡¯s richest people became a major financier of conservative causes and political candidates, has died at age 79, his brother said on Friday.

Charles Koch, Koch Industries Inc¡¯s chairman, disclosed the death in a statement that touched on his younger brother¡¯s lengthy battle with prostate cancer and his philanthropic contributions to medical research, education and the arts.

¡°He will be greatly missed, but never forgotten,¡± Koch said in a statement addressed to employees. ¡°David was proud of the extraordinary work you all have done to make Koch Industries the successful company that it is today.¡±