Casino kingpin Ismail Hossain Chowdhury Samrat was taken to Suryamukhi building of the Keraniganj Central Jail after he was released from the National Institute of Cardiovascular Diseases (NICVD) on Saturday morning.
The superintendent of the jail, Mahbubul Islam, has confirmed this to the Business Standard.
Sources at the jail said that terrorists, militants and people charged for notorious crimes are kept in the Banaphul, Bakul, Shapla and Suryamukhi buildings.
Almost 400 dangerous criminals can be accommodated in the cells there. These four high security prison buildings are surrounded by a wall that is almost 18 feet high, and has an additional two feet of sensor wires on top.
Earlier on Tuesday, Samrat was admitted to the NICVD with chest pain.
He was arrested from the Chauddagram area of Cumilla for alleged involvement in running casino business at sports clubs in the capital. Samrat reportedly tried to flee the country through the Cumilla border with India before he was arrested.