to write back in 1956: "This period of "mind changing" bothered me", and "this change in the operating policy of the UFO project was so pronounced that, I like so many other people, wondered if there was a hidden reason for the change. Was it actually an attempt to go underground - to make the project more secretive?" Death In what one paper rerred to as a "sudden" death, Ruppelt succumbed to a heart attack on September 15, 1960, at the age of 37. He was survived by mother Mrs Bessie Ruppelt, wife Elizabeth Anne, and daughters aged 9 and 4. References Notes Bibliography Clark, Jerome. The UFO Book: Encyclopedia of the Extraterrestrial. Detroit, Michigan: Visible Ink, 1998. . Hoyt, Diana Palmer. "UFOCRITIQUE: UFOs, Social Intelligence and the Condon Committee". Master's Thesis, Virginia Polytechnic Institute, 2000. Hynek, J. Allen. The UFO Experience: A Scientific Inquiry. Chicago, Illinois: Henry Regenery Company, 1972. Jacobs, David Michael. The UFO Controversy In America. Bloomington, Indiana: Indiana University Press, 1975. . Ruppelt, Edward J. The Report On Unidentified Flying Objects. New York: Doubleday & Company, Inc., 1956, First Edition; London: Victor Gollancz, 1956. 2nd, expanded edition New York: Ballantine, 1960. Tulien, Thomas. Proceedings of the Sign Historical Group UFO History Workshop. Scotland, Connecticut: The Sign Historical Group, November 2001. External links 1923 births 1960 deaths Ufologists American UFO writers United States Army Air Forces personnel of World War II Recipients of the Distinguished Flying Cross (United States) United States Air Force officers People from Iowa Military personnel from Iowa Iowa State University alumni American aerospace engineers United States Army Air Forces officers Recipients of the Air Medal 20th-century American non-fiction writers 20th-century American engineers United States Army reservists United States Air Force personnel of the Korean War