Tamim Chowdhury got entangled in militancy while residing in Canada; he came to Dhaka on 5 Oct, 2013, and tried to bring militants on one platform.

At this time, he launched an organization called: Junud al Towhid. But failing to make an impact, contacted some members of the old JMB and later formed the IS ideology based group, New JMB, says investigation report of the Gulshan Holey Artisan attack.
On Saturday, head of Counter Terrorism and Transnational Crime Unit, CCTC, Monirul Islam, said: once in Dhaka, Tamim managed to pull some ultra-radical elements of JMB and began target killings.”
The investigating officer of the Holey Artisan killing says that Tamim met Abdus Samad from Chapainawabganj and introduced him to others.
Reportedly, the New JMB had five separate wings: military, accounts, explosives, finance, media and transport. The military section had four sub-divisions: Fidayi, Ingimasi, Ishtihadi and Lone Wolves.
The attack on Holey Artisan was an Ingimasi attack. Aimed at creating a hostage situation that would ensure international attention.
Before coming to Bangladesh, Tamim was in Syria where he is believed to have had contacts with Syrian militants. After the IS declared Khilafat, he came and met young people with similar outlook from wealthy and English medium education backgrounds, through a person called Jilani, who was later killed while fighting for IS in Syria.
It’s believed that the attackers of the Holey Artisan were selected by Tamim and all of them received physical training. The team included: two youths from lower middle class, Shafikul Islam Uzzal and Khairul Islam Payel; the other three: Rohan, Nibras and Mobasshar came from upper echelons of society.
They had plans to attack a restaurant with foreigners so world media attention would fall on Bangladesh, said CCTC head Monirul Islam.
Tamim was educated and had a hypnotic effect on others, said a CCTC official.
He also brought money from abroad and since the organization had adequate funds, Tamim’s leadership was accepted.
Tamim realized that with one attack he would be the centre of discussion worldwide and therefore, sent photos of the Holey Artisan siege, which were uploaded to the so called IS platform, AMAK Agency, to claim responsibility.

Tamim thought that Holey Artisan would create international coverage and, at the same time sustain the morale of the new recruits for his militant outfit, added Monirul Islam.
On July 1, 2016, Tamim and his group took over Holey Artisan restaurant in Gulshan and killed a total of 22 persons: nine Italians, 7 Japanese, 1 Indian, 1 US citizen of Bangladeshi descent, two Bangladeshis and two members of the police. One person arrested on suspicion of having links with the attack died on July 8.
The siege ended with an army commando mission the following morning. All five radicals and a pizza chef were killed.
On 8 July, the Gulshan police lodged a case under counter terrorism law. Mastermind of the attack, Tamim Chowdhury, and two cohorts was killed in a police operation in Paikpara, Narayanganj, on September 27, 2016.