Carl Robert Siebentritt Jr.

Carl Robert Siebentritt Jr. passed away peacefully on Sunday, June 9, 2019 at the age of 96, surrounded by his family in his Lucketts, Va home. He is survived by his six children, son Carl III (Irida), daughter Gretta, son Peter (Andrea), son Joel (Carter), daughter Heidi (David), and daughter Krista (Scott), as well as adoptive son Thai Pham. In addition, he leaves behind thirteen grandchildren— Irena (Edher), Jesse, Henry, Lila, Chris, Sam, Grace, Kate, Peter, Ella, Jacob, Claire, and Matthew, and one great-grandchild, Isabel. Carl was preceded in death by his beloved wife, Elise. The family will celebrate his life with a private memorial service at a later date. Carl was born on August 14, 1922, in Jersey City, New Jersey. He was an Army Combat Engineer in World War II, participating in the Central Europe and Rhineland Campaigns. Upon returning from the War, Carl earned a BS in Mechanical Engineering and a MS in Physics from the University of Cincinnati. A physicist and inventor with expertise in nuclear preparedness, he holds multiple patents for radiological instrumentation, including the field-grade pocket dosimeter used by the military and first responders. Carl left private industry in 1962 to join the Department of the Army's Civil Defense Agency, which later became the Federal Emergency Management Agency, retiring after 37 years of distinguished Federal service. Carl was passionate about running. He completed 14 Marine Corps Marathons and was a fixture at the annual Rotary Resolution 10K Race, running well into his eighties. Carl loved his regular workouts at Ida Lee Rec Center until his health began to decline this year. He studied wildflowers and mushrooms, and was a lifelong fisherman and birdwatcher. Carl and Elise were founding members of Pilgrims After Christ (PAX), an intentional eucharistic Catholic community in McLean, dedicated to meaningful liturgy, religious education, and social justice outreach. Carl was a member emeritus of the National Health Physics Society, a member of the Scientific Research Honor Society (Sigma Xi), a member of Lucketts Ruritan Club, and a volunteer at Loudoun Hunger Relief. Carl will be remembered for his generosity and his singular sense of humor. Above all, Carl valued his family and friends, whom he loved deeply. Donations in Carl’s memory should be directed to: Pax Christi Fund for Peace ( or Franciscan Mission Service (

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