The gang that took part in the killing of secular blogger Ananta Bijoy Das had members from both in and outside Sylhet, law enforcers believe.
At least one of the four assailants is from Sylhet, as he spoke in local dialect while fleeing the murder scene on Tuesday morning, said a police official involved with the investigation.
Investigators said the gang members from outside must have stayed in Sylhet for at least a couple of months to follow Ananta and finalise the killing plan.
“This can't be done without supports from local mentors,” said the official.
He spoke on condition of anonymity because it was too early to comment.
“We are going to each hotel and mess of the city to know about boarders. Especially, we are trying to learn who rented rooms for one or two months and left recently,” he added.
Rahmat Ullah, additional deputy commissioner (media) of Sylhet Metropolitan Police (SMP), said the lone witness to the killing, tea vendor Abdus Sobhan, heard one of the killers shout at him in local dialect as he tried to approach them.
“But it does not mean that the rest are outsiders,” Rahmat, also the SMP spokesperson, told The Daily Star yesterday.
Rahmat and some other police officers suspect Islamist militants behind Ananta's murder, like in the murders of bloggers Avijit Roy and Oyasiqur Rahman in Dhaka.
Law enforcers in the capital on several occasions said Ansarullah Bangla Team, an active militant outfit, were behind their murders.
Sylhet once was a hub of different militant outfits. A number of top militants have been arrested there since 2007, including the chief of banned militant outfit Jama'atul Mujahideen Bangladesh Shaikh Abdur Rahman. He was executed in 2008, a year after his arrest.
There has been hardly any visible militant activity in the area in the last few years. But investigators say militants might have changed their locations to operate secretly.
“The operation to kill Ananta is a proof of their clandestine activity,” said another police officer of SMP.
Immediately after the murder, police put check posts at every entry and exit points of the city to nab the killers. Police and intelligence agencies have been conducting raids in the city but are yet to arrest or identify anyone.
Police are also looking for the machetes and masks used by the killers.
Yesterday, police collected video footage of the Pubali Bank branch where Ananta worked as an assistant development officer for about two years.
Police suspect the killers visited him at the bank posing as clients.
Ratneshwar Das, elder brother of Ananta, said they had no idea about the killers. “But we are sure he was killed for his writings and we want justice.”
Meanwhile, demonstrations continued in the city demanding the arrest and punishment of the killers.
Udichi Sylhet unit organised a protest rally in the city's Chaohatta area in the afternoon where speakers accused law enforcers of failing to protect free thinkers and bloggers.