De Haan was assassinated on 30 June 1924 in Jerusalem by members of Haganah, and final responsibility was attributed to Zionists alarmed by his political activities in favour of a settlement with Arab leaders.
The 1985 publication of De Haan: The first political assassination in Palestine, by Shlomo Nakdimon and Shaul Mayzlish, revived wider interest in his assassination. Nakdimon and Mayzlish were able to trace the assassin, Avraham Tehomi (1903–1990), then a businessman living in Hong Kong. Tehomi was interviewed for Israeli TV by Nakdimon and openly stated: "I have done what the Haganah decided had to be done. And nothing was done without the order of Yitzhak Ben-Zvi (who later became the second president of Israel 1952-1963)...
