[4] Al-Mamun was born on 12 January 1964 in the village of Shreehail under Sullah Upazila in Sunamganj District.

IGP in PSpecial Branch from 2018 to 2020[6] Mamun was promoted to Additional IG grade-I in October 2021.

[10] At the aftermath of the non-cooperation movement and the overthrow of Sheikh Hasina, his contract was cancelled on 6 August 2024 and Md.

[14] On 17 September, he was arrested in six more murder cases filed with Uttara East and West police stations.

Along with seven others, Al-Mamun was accused of crimes against humanity, genocide and overseeing massacres during the response to the non-cooperation movement.

[16] On 10 December 2021, the U.S. Department of the Treasury added Al-Mamun to its Specially Designated Nationals (SDN) list over the Killing of Ekramul Haque under the Global Magnitsky Act.