In an interview with NDTV India, Imtiaz Khan Babul said his son, 21-year-old Rohan Imtiaz, was one the five attackers who stormed the Holey Artisan Bakery, killing 21 people as well as two police officers, before later being killed in a police raid.
"I saw the picture released by ISIS again and again before I confirmed it was my son. I was stunned to see it," said Babul, an Awami League politician.
Imtiaz's shock over his son's part in the carnage at the Dhaka cafe echoed that of another attacker's father.
Meer Hayet Kabir, father of gunman Meer Sameh Mobasheer, told CNN on Monday
, "This cannot be....I still want to believe that Sameh is not in that body. I still want to wait and hope."
Babul told NDTV that he had "never noticed anything abnormal or got any indication" of his son's involvement with radical militants.
"I never saw him reading or accessing any jihadi material," he said.
"We have a common computer," the father said. "But he had a mobile. I don't know whether he was reading jihadi material through that," adding "someone must have planted these thoughts in his head".
Young, well-educated, middle class
The revelation that the attackers were young, well-educated men who attended top schools and received secular education has surprised many.
In an earlier interview with CNN
Faiz Sobhan, of the Dhaka-based think tank Bangladesh Enterprise Institute, called the background of the attackers "puzzling".
"They were normal, regular guys who hung out at cafes, played sports, had Facebook pages," he said.
However, the profile of the Dhaka gunmen correlates with findings of studies in the U.S. and Europe by researcher Zeeshan ul-hassan Usmani, George Washington University and the Brookings Institution.
All the research showed that, contrary to popular belief, more than 70% of ISIS recruits were from middle class or wealthier backgrounds.
Many came from secular families, and weren't particularly religious before radicalization, learning ISIS ideology on websites like YouTube.
"Sixth gunman" turns out to be chef
Bangladesh police admitted on Wednesday they shot a cafe chef dead during the attack, thinking he was a terrorist.
Police had said earlier there were six gunmen involved in the siege but have since revised the number to five.
Saiful Islam Chowkidar was shot as he was trying to flee the cafe with others, Police Inspector General Shahidul Hoque told CNN via text message.
The victim had been wearing a restaurant uniform but was running away near the attackers when authorities stormed in.
"The restaurant owner is claiming that he was their employee....He was killed by the snipers with miscreants and his dead body was lying with the dead bodies of other miscreants,' Hoque said.