Joseph Hartlooper died in Camp Westerbork at age 81 on 3 February 1943. He was buried in the Jewish cemetery in Assen on 5 February 1943.
Jewish Historical Museum, Documents collection, inv.nr 3397; Death register of the Jewish community Assen
The funeral records at the Jewish cemetery in Assen reveal that Joseph Hartlooper was buried there.
This person is commemorated on a memorial in Assen. More information on this memorial can be found (in Dutch) on the website of the Nationaal Comité 4 en 5 mei.