Kaiser was born in the Mazupur village as Abu Nayeem Mohammad Shahidullah. He studied at Presidency College, Kolkata and obtained a bachelor's degree in economics with honours. Later, he enrolled in master's of arts at Calcutta University but did not complete the degree.
Kaiser was active in politics and cultural movements from his student days. Following the formation of Pakistan in 1947, he joined the provincial Communist Party of East Pakistan. He started working as a journalist in 1949 with the Ittefaq in Dhaka. In 1952, he participated actively in the Language Movement. For his political role in the movement for protection of Bengali language, Kaiser was arrested on 3 June 1952. He was later jailed for three and a half years. Right after his release in 1955, he was again arrested and jailed on a political crackdown on activists. A few years later he was released. In 1958, Kaiser joined as an associate editor of The Sangbad – a Bengali language daily – where he worked for the rest of his life. When the military coup of 1958 put Ayub Khan in power, and martial law was proclaimed, Kaiser was arrested again on 14 October 1958 and remained in jail for four years till his release in September 1962.
Disappearance
Kaiser collected medicine and food and delivered those to the posts such as one being Begum Sufia kamal's house, from where the freedom fighters picked those up for their training outpost. At the end the Bangladesh Liberation War of 1971, the Pakistan Army and its local collaborators initiated a plan for killing the leading Bengali intellectuals. As a part of it, Kaiser was rounded up on 14 December 1971. He never returned, nor was his body ever found. It is assumed that he was executed along with other intellectuals. His brother, Zahir Raihan, a notable film-maker, also disappeared while searching for Kaiser. In early December 1971, Kaiser cautioned Sufia Kamal to leave Dhaka but he himself did not leave and got caught in the hand of the Pakistani Army. On 3 November 2013, Chowdhury Mueen-Uddin, a Muslim leader based in London, and Ashrafuz Zaman Khan, based in the United States, were sentenced in absentia after the court found that they were involved in the abduction and murders of 18 people – nine Dhaka University teachers, six journalists including Kaiser and three physicians – in December 1971. Chowdhury Mueen-Uddin denied the charges in an interview aired by Al Jazeera in August 2013.
