An overnight security raid at Kalyanpur area in Dhaka four days ago provided police the clue to identify Tamim Chowdhury as the architect of the recent Islamist assaults, a police officer familiar with the investigations told PTI on anonymity.
"We found Tamim Chowdhury to be the mastermind of the two (back-to-back terrorist) attacks... A manhunt was launched to track him down as we think, he now lives in Bangladesh since his return (from Canada) three years ago," he said.
A Bangladeshi newspaper earlier reported that Chowdhury appeared as the leader and main financer of a reorganised Jamaatul Mujahideen Bangladesh (JMB). Bangladesh earlier attributed the two attacks to the clandestine outfit.
The report suggested that Chowdhury was working as the link between the reorganised JMB and the ISIS, which claimed the responsibility for the July 1 attack when the terrorists killed 22 people, among them 17 foreigners including an Indian and two police officers.
Police's counter-terrorism unit's chief Monirul Islam had said investigators got names of several suspected masterminds behind the two "interlinked attacks" but efforts were underway to confirm their true identities.
Bangladesh earlier said they found no proof of ISIS link to the country's terrorist attacks.