Donald "Don" Alan Leonard, 71, a 32-year resident of Upper Marlboro, MD and previously Hampton, VA, died on Monday, June 10, 2019, at Washington Hospital Center. Born April 26, 1948, in Yonkers, NY to the late Edmund and Aileen Voges Leonard, he graduated from Charles E. Gorton High School, New York University with a bachelor degree in Engineering, and the University of Southern California with a masters degree. Don served his country for over 20 years in the United States Air Force. Following his military career, he went on to work at the Smithsonian Museum of American History and the United States Naval Academy Museum. Don was a longtime member of St. Mary of the Assumption Catholic Church in Upper Marlboro, MD, where he served on the Parish Council. His other memberships included the Air Force Association, and a was an active volunteer with the USO. Don enjoyed military history, model trains, and traveling. In addition to his parents, he was preceded in death by a brother, Kenneth Leonard. Don is survived by his wife of 35 years, Lorraine Leonard; a son, Thomas Leonard of Upper Marlboro, MD; and a sister, Gwen Leonard of Harvard, MA. Friends are invited to celebrate Don's life on Monday, June 17, 2019, from 10:30 am until a Mass of Christian Burial is offered at 12:00 pm at St. Mary of the Assumption Catholic Church, 14908 Main St., Upper Marlboro, MD. Interment will be held at Arlington National Cemetery at a later date. In lieu of flowers, contributions may be made to Saint Kateri Tekakwitha Novitiate House of Formation, 1714 Crain Hwy., Upper Marlboro, MD 20774. An online guestbook is available by visiting the link on this page.