Egosi died of Parkinson's disease Oct. 11. He was 83.
Born in Poland in 1929, Egosi and his family moved to Paris when he was 7 years old. After the Nazis seized the French capital in June 1940, the persecution of Jews there began; Egosi was captured and forced into the Beaune-la-Rolande concentration camp outside Paris.
His father, a chemical engineer, secured his son's release in 1942 by promising to create a process that retards the freezing of plane fuel for the then-fascist Italian government, the German occupier's ally, said Egosi's eldest son, Nathiel.
He exchanged the process for his son's freedom.
"A German soldier showed up at the concentration camp and requested my father to be released," Nathiel Egosi, of Sag Harbor and Dix Hills, said. The family was reunited in Italy and settled in Rome.
After Allied troops liberated Rome in 1944, Charles Egosi traveled to Ramat Gan, now part of Israel, and later fought in the War of Independence that established the state of Israel in 1948.
He returned to France in the 1950s, studied architecture at Paris' Ecole Superieure des Arts Modernes, and met Lydie Calmels. The couple immigrated to the United States and married in Brooklyn in April 1956.
They settled in Forest Hills while Charles Egosi worked for a Manhattan-based architecture firm, Finn Jenter, and, in 1958, Nathiel was born. Two other sons would follow: Richard in 1962 and Yoram in 1968.
By 1969, the family began living year-round at their former summer home in Sag Harbor. Egosi established a prolific practice in Sag Harbor and Stony Brook that helped erect a number of iconic edifices now dotting western Suffolk and the East End.
He designed and improved many structures and homes in the village, including the Sag Harbor Fire Department headquarters, Pierson High School and the Sag Harbor Inn, which he owned and operated in his later years.
Active in the Sag Harbor community, Egosi served as president of Temple Adas Israel, a village planning board member, a village building inspector and co-author of the Sag Harbor master plan.
Egosi spoke six languages fluently, said Nathiel Egosi, describing his father as "a constant learner."
"He had incredible drive," Nathiel Egosi said. "He was very passionate about what he believed in. There was no gray. Everything was black or white. He was very dedicated to his work, his family, to his country and to Israel and Judaism."
Besides his wife and son, Nathiel, Charles Egosi is survived by son, Richard of Sag Harbor and Dresher, Pa.; and eight grandchildren.
Burial was in Jerusalem on Oct. 12.