Friedman lost almost his entire family during the Holocaust. He survived by escaping from a Labour Camp of the Radom Ghetto in occupied Poland. Upon the liberation of Poland in mid-January of 1945, Friedman joined the Polish Police Force under an assumed identity and began his life’s work: hunting those who participated in the German crimes.
In 1946 in Vienna, Friedman was active with the organizations Aliyah Bet and Haganah which – partly with the use of violence against the British Mandate Authorities – promoted emigration to Palestine. He joined forces with Simon Wiesenthal and started tracing the whereabouts of German perpetrators of which a total of 250 were captured due in part to their work.