Born in 1934, Horner completed his Bachelor of Science in business at the University of Kansas in 1956. According to a statement his former firm released on news of his death, Horner started work after graduation at the Kansas City office of Peat Marwick Mitchell & Company. He was made a partner in 1964, heading the Miami, Fla. office before relocating to Europe. He was head of the firm’s Frankfurt, Germany office until he became the CEO of Peat in 1984. While CEO, he oversaw the 1987 merger of Peat Marwick Mitchell & Company and Klynveld Main and Goerdeler, creating KPMG Peat Marwick. Horner left the firm in 1991, and went on to serve on the boards of such corporations as ConocoPhillips, American General Company, Atlantis Plastics, UT Starcom Inc., chairing the board of directors of USA Holding Corp. and the Asia Pacific Wire Cable Ltd.