Indian intelligence says they have received 'critical inputs' about the presence of four top Neo-JMB men who are active in West Bengal.
"We have been told by Bangladesh intelligence that these four JMB activists are supplying weapons and finances to the group's operational units in Bangladesh," a senior official of India's Intelligence Bureau (IB) said.
The four have been identified as Sohel Mahfuz, who heads the neo-JMB in eastern India, and his close accomplices Shariful Islam, Mamunur Rashid and Junayed Khan.
The IB official said these four had fled Bangladesh after the Holey Artisan Bakery attack in July last year.
"But Marzan stayed back to conduct operations, only to end up getting killed in an encounter in Dhaka on Friday," the IB official said.
Bangladesh police said Nurul Islam Marzan was one of the masterminds of the Dhaka cafe attack, in which 20 people were killed -- mostly foreigners.
He was killed early on Friday at Dhaka's Mohammadpur with another Neo-JMB operative Saddam Hossain in what the counterterrorism officials describe as a 'shootout.'
Police had earlier said that the grisly pictures from Holey Artisan attack were sent out in consultation with Marzan.
Earlier, Bangladeshi-Canadian Tamim Ahmed Chowdhury, who was singled out by police as the Neo-JMB chief and the key player in the recent terror activities in Bangladesh, and two others were killed in a police operation in Narayanganj on Aug 27.
Several Dhaka-based media reported that police had detained Marzan a month after the cafe attack.
Meanwhile, Saddam's family claimed after Friday's shootout that he was picked up by plainclothesmen on the night of Apr 14 last year.
The West Bengal Police Special Task Force (STF), which recently arrested six Neo-JMB activists from the state and Assam, admitted that these four JMB activists were still at large.
"We have stepped up operations to nab these four. We have got some idea about their activities from the six we have arrested," said a STF official.
Documents seized from Marzan seem to indicate he was in touch with the cell run in West Bengal by Sohel Mahfuz.
"Bangladesh intelligence says it is now sure Mahfuz and his cell is procuring weapons for the Neo-JMB activists in Bangladesh," the IB official said."So catching these four is top priority for us now."
Bangladesh's counter-terrorism officials have said before that the AK-22 rifles used by JMB have been procured from India.
India's National Investigation Agency (NIA) accepted that during their investigation into JMB activities, according to a news agency.