In 1944 was transferred to Jerusalem as deputy to the District Commander, Eliyahu Lenkin. After Lenkin's arrest, Efrat was appointed in his stead.
In August 1945 , he was arrested by the British, and a body-search revealed a slip for a parcel to be collected from the Atid taxi company. The parcel, containing detonators sent from Tel Aviv, served the prosecution as evidence at his trial before a military tribunal. He was convicted and sentenced to seven years imprisonment.
Freed two years later by his comrades during the Acre jail break.