
The deceased was identified as Abdul Mannan, 42, son of Joynal Abedin of Uttar Balukhanda area of Nawabganj in Dhaka district.
According to prison authorities, Mannan was in custody in connection with a narcotics case.
Prison guard Biplob said Mannan suddenly sick inside the jail in the morning.
He was taken to the emergency department of Dhaka Medical College Hospital (DMCH) where the attending physician declared him dead, reports UNB.
Inspector Md Faruk, in-charge of the police camp at DMCH, said the body has been kept at the hospital morgue for an autopsy.
An inquest report will be prepared in the presence of an executive magistrate before the post-mortem examination, he said.
After completion of the legal formalities by the prison authorities, the body will be handed over to the deceased's family, he added.