Roy was elected to the central committee of the Krishak Samiti and the Communist Party in 1968. During this period he remained in hiding from the police and helped organize protests against President Ayub Khan. He campaigned for the Communist Party candidate in the 1970 Pakistan general election. Following the start of the Bangladesh Liberation war in 1971, he moved to India and trained as a member of the Mukti Bahini. He helped organize training in the Mukti Bahini Balat camp in Meghalaya, India. He helped organize guerrilla forces composed of left wing political supporters to fight the Pakistan Army in the Bangladesh Liberation war.