Hadisur Rahman Sagor, one of the most wanted suspects in last year's Gulshan café attack, left a militant den in Ghop Nawapara area of Jessore just two days before police busted it yesterday.

Law enforcers, however, managed to capture his wife Khadija Akter after she along with her three kids came out of the den at one stage of the around 15-hour raid, said Ikramul Habib, additional deputy inspector general (Khulna range) of police.

She is the younger sister of Nurul Islam Marzan, one of the café attack masterminds, and a distant niece of another dreaded militant and café attack bomb supplier Sohel Mahfuz alias Hatkata Mahfuz.

Marzan was killed in a shootout with police in Dhaka in January and Sohel was arrested in Chapainawabganj on July 8.

Khadija's husband Sagor was among the suppliers of arms and explosives used in the Gulshan attack.

Acting on intelligence from Lawful Interception Unit of Police Headquarters and Bogra District Police, law enforcers launched the operation code-named Operation Melted Ice around 2:00am yesterday. The families living in other flats of the four-storey building were evacuated within a short period.

Responding to police's call for her to surrender, Khadija, 19, dropped a suicide vest in her flat on the first floor of the building and walked out of it around 3:05pm, according to police.

She decided to surrender after cops had brought her parents to the spot from Pabna as she wanted. Her daughters Sumia, 5, and Suriya, 3, and son Raju, aged about one and a half years, were with her.

Police later recovered three suicide vests and as many maps, presumably sketches of buildings targeted by militants, and a desktop computer from the militant hideout.

“The suicide vests were so powerful that each of them could have killed 40 to 50 people if exploded in a crowded place,” said Rahmat Ullah Chowdhury, additional deputy commissioner of the CTTC's bomb disposal unit, who led his team to the operation.

“A large hole was created on the first floor of the militant hideout when the vests were detonated,” he added.

Another official of the Counter Terrorism and Transnational Crime Unit (CTTC) said deadly explosive triacetone triperoxide (TATP) was used in making the vests.

Once a member of Jama'atul Mujahideen Bangladesh (JMB), Sagor joined the “Neo JMB” after Bangladeshi-Canadian Tamim Ahmed Chowdhury along with some JMB leaders set up the ultra-radical militant outfit on September 23, 2015, reportedly inspired by global terror outfit Islamic State.

Tamim, chief coordinator of the “Neo JMB”, and some other leaders of the militant outfit planned and executed the country's deadliest terrorist attack at the Holey Artisan Bakery in the capital's Gulshan on July 1 last year. The attack left 20 hostages, including 17 foreigners, and two police officials dead.

Tamim along with two of his associates was killed during an operation at a Narayanganj militant den on August 27 last year.

Although most of the “Neo JMB” leaders have either been killed or arrested in anti-terror operations, Sagor, also known as Joypurhat Sagor, managed to escape arrest, CTTC officials said.

“An expert in bomb-making, Sagor is now the military commander of 'Neo JMB' and one of the most notorious militants among those still eluding arrest,” a CTTC official told The Daily Star.

Identifying himself as Moshiur Rahman, Sagor rented the flat in Ghop Nawapara area and had been living there with his family for about a year, said a CTTC official who took part in the operation.

He is trying to reorganise the “Neo JMB”, CTTC officials said.

After cordoning off the building early yesterday, law enforcers using loudspeakers tried to persuade Khadija to surrender, being confirmed that there were three kids inside.

Ignoring the call, she put on a suicide vest. Around 12:10pm, she set a condition that her parents must appear there.

Minutes after her surrender, police put Khadija and her kids in a white microbus and drove it away.

Alongside Jessore police, members the Dhaka Metropolitan Police's SWAT and bomb disposal unit took part in the operation.

The raid created panic among the neighbouring people, with police off-limiting the spot and nearby area to public. Journalists were allowed to stay at a safe distance.