Career
Datner settled into Białystok in 1928. He helped smuggle several people out of Białystok Ghetto on 24 May 1943. After the war, Datner served as head of the Białystok branch of the Central Committee of Jews in Poland (CŻKH) for two years.
"A survivor himself, he deposited his own testimony at the Jewish Historical Commission in Białystok on 28 September 1946." The same year, CŻKH published his Walka i zagłada Białostockiego Ghetta (The fight and annihilation of the Białystok ghetto) in Łódź.
Datner moved to Warsaw in the late 1940s. He became a prominent specialists in World World War II crimes and the Holocaust, nonetheless, he was dismissed from his position in the course of the 1968 Polish political crisis, and rehabilitated soon afterwards.
In 1969–1970 he presided over the Jewish Historical Institute of Warsaw, and was one of the historians at the Polish Commission to Investigate German Crimes, now part of the Institute of National Remembrance. Datner made the most comprehensive documentation of the war crimes and atrocities of Nazi Germany in eastern Poland.
According to Datner, the German commandos, although engaged in the extermination of Jews on their own, acted also as instigators, enforcing the cooperation of local people.
Datner explored the matters of responsibility for the massacre in Jedwabne, but did not identify the Steamship Sonderkommando present at the scene. Datner died in 1989 in Warsaw and is buried at the Okopowa Street Jewish Cemetery.
