Judge Saifuzzaman Hero of a Khulna tribunal that hears cases over crimes related to disruption of public security delivered the verdict on Monday.
He also fined the convicts Tk 10,000 each, Public Prosecutor Arif Mahmud Liton said.
Humayun was the editor of a local newspaper the Daily Janmabhumi and the president of Khulna Press Club.
He was killed in a bomb attack at the entrance of the newspaper’s office in Shantidham intersection of Khulna city on Jun 27, 2004.
The convicts are ‘Zahid’, ‘Nazu’ alias ‘Ripon’, ‘Rimon’, ‘Swadhin’ and ‘Masum’ alias ‘Jahangir’ - all members of the banned extremist group Purbo Bangla Communist Party (ML-Janajuddho).
Jahangir is on the run while the four others were present at the courtroom during the delivery of the verdict.
“We are not satisfied with the verdict. We expected that maximum punishment will be secured,”
SM Zahid Hossain, brother of Humayun and president of the Khulna Press Club, demanded re-investigation saying they were not happy with the verdict as they expected death penalty.
The investigators could not find the name of the mastermind and financier of the attack.
The police had opened two cases over the killing of Humayun – one under the Explosives Act and another on murder charges.
The court acquitted all seven accused in the murder case on Feb 13, 2008.