On 6 May 1947, Farran's unit arrested 16-year-old Alexander Rubowitz, who was putting up posters in Jerusalem for the Jewish underground organisation the Lehi. Rubowitz was taken by Farran's team, and tortured to force him to surrender his friend's names. The boy did not survive the torture. His body was dumped and never found. Suspicions of Farran's involvement were first raised after a grey trilby hat, bearing an indistinct name compatible with his, was found near the street corner where Rubowitz was seen being pushed into a car. In 2004 British secret documents were revealed that included a statement by Fergusson, written at the time of the event, to the effect that Farran confessed to Fergusson of the murder. Fergusson then reported the incident to Gray.