Born in Daruvar, Croatia, Frankfurter was the son of the town's rabbi. After completing his basic education he began a study of medicine, for which he traveled to Leipzig and Frankfurt. The rise of Nazi power in Germany compelled him to relocate to Switzerland to continue his studies, and he settled in Bern in 1934.
Having become convinced of the danger posed by the Nazis, Frankfurter kept an eye on Gustloff, head of the Foreign Section of the Swiss Nazi party, who ordered the publication of the Protocols of the Elders of Zion in Switzerland. This culminated in the assassination which occurred in Davos on February 4, 1936. Frankfurter was put on trial for the shooting in Chur on December 9 of that year.
Although the assassination was not unfavorably received by the largely anti-Nazi population of the country, the Swiss government prosecuted the case strictly, owing to concerns about its status of neutrality. Frankfurter was convicted of the killing and sentenced to an eighteen-year prison term.
As the war came to a conclusion, however, Frankfurter applied for a pardon on February 27, 1945 and it was granted on June 1, with the stipulation that he leave the country, and also pay restitution and court costs. After his release he traveled to and settled in Tel Aviv.
Frankfurter published his memoirs in 1950. The Swiss government rescinded the order of exile in September, 1969.