Former minister Anwar Hossain Manju was released hours after his detention on Monday.
Manju was detained by the Dhaka Metropolitan Police's Detective Branch (DB) in the Dhanmondi area in the afternoon.
Manju is an accused in five cases filed over violence during the Anti-discrimination Student Movement.
He is a former MP for Pirojpur-2 and former minister of water resources.
Anwar Hossain Manju is the leader of a Jatiya Party faction known as JP (Manju).
His father, Tofazzal Hossain Manik Mia, was a prominent politician and the founder of The Daily Ittefaq.
Anwar Hossain Manju served as the editor of The Daily Ittefaq from 1972 to 1975.