Otto was born in 1921 in Belvidere, NJ. Graduating from West Point, he joined the Army Corps of Engineers and was posted to Germany in 1944. He obtained a Masters in Engineering from Iowa State University in 1949. In 1947 he married Mary Alice Webber; they had three sons Jean, Leon, and David, who survive them.
Otto became a pacifist and resigned his commission in 1953. He entered civilian engineering, where he helped construct bridges across the Missouri and Mississippi rivers, building his own house from foundation to roof in Kansas City in his spare time. Then he came west to work for PG&E in San Francisco, doing earthquake design. He was a member of the Great Books Society and an enthusiastic chess player.
As a member of the Society of Friends, Otto and Mary were active war resisters during the Vietnam era.
Otto was one of the designers and founders of the Friends House retirement community in Santa Rosa, where he and Mary spent their last decades. They continued to travel in retirement, visiting Spain and Japan as well as many U.S. locations.
Otto died at Friends House on April 30, 2016.