David Marler has had a lifelong interest in the UFO subject and has actively investigated and researched it for 30 years. He joined The Mutual UFO Network (MUFON) in 1990 as a Field Investigator Trainee. Since then, he has served as Field Investigator, State Section Director, as well as Illinois State Director. David is an internationally recognized independent UFO researcher.​​During his tenure with MUFON, he had conducted numerous investigations into alleged UFO sightings and related experiences. He has discussed the subject of UFOs on many radio and television news programs over the years. He has also lectured on the subject to various school and adult audiences including at the university level.David has one of the largest personal libraries of UFO books, journals, magazines, newspapers, and case files from around the world that covers the last 75+ years. With this, he has been examining the detailed history of UFO sighting reports and related patterns.Recent evidence of his historical research is his newly-published book, Triangular UFOs: An Estimate of the Situation. Here, he has provided a comprehensive analysis of triangular UFOs. He has collected, collated, and analyzed hundreds of reports. In the process, he has created a detailed profile of these objects and written a rich narrative of their history. He tackles the arguments made by skeptics that dismiss these triangular UFO reports outright. He also addresses the claims of so-called insiders who claim these objects are a creation of the U.S. military.He strives to have an open mind regarding the UFO phenomenon. However, he also acknowledges the need for a skeptical approach when examining each individual UFO report.