Rakib Hasan, who was arrested hours after he was freed along with two other fellow militants in an armed attack on a prison van, was killed in the crossfire at Mirzapur upazila.
"He was killed in the crossfire as the shootout started when the miscreants attacked us while we were raiding an area along with him in search of the two other fugitive convicts," police officer Golam Mostafa told reporters.
According to Mostafa, a joint team of law enforcement agencies took Hassan along with them to track down the two fugitive JMB operatives - Salauddin Ahmed and Zahidul Islam alias "Boma" Mizan - to recapture them.
He said the suspected JMB militants started firing gunshots "prompting policemen to use their guns too", resulting in the accidental death of Hassan, a member of the the banned group's Majlis-e-Shura.
Bangladesh witnessed the growth of several Islamist militant outfits including JMB and Harkatul Jihad al Islami (HuJI) in the recent years.