Isaac van Westerborg was a son of Nehemia van Westerborg and Esther Huisman. He married in 1924 in Rotterdam. This marriage was dissolved by a divorce in 1932.
Stadsarchief Amsterdam, archiefkaart Isaac van Westerborg
Isaac van Westerborg was killed in concentration camp Amersfoort on 17 August 1942. He was an office-clerk.
Death books of Camp Amersfoort; these can be consulted at the website of the National Memorial Camp Amersfoort