Eliazar Koster appears on a handwritten list of all people who worked for the Dutch-Jewish Community in Haarlem during the early years of the war. A photograph remains of each official. Eliazar Koster was a night watchman for the synagogue of the Dutch-Jewish Community in Haarlem.
Eliazar Koster was married. He and his wife lived at 56 Duivenvoordestraat in Haarlem.
Jewish Historical Museum, Documents collection, inv.nr 1001