Investigators have identified the militant group involved in the killing of secular writers, bloggers, teachers, members of religious minorities and foreigners.
In many of the attacks, the victims have been hacked to death with machetes and in some cases beheaded.
The members of Ansar Al Islam, an Islamic religious extremist group, previously known as Ansarullah Bangla Team, were involved in the killing of secular writers and bloggers, sources told the Daily Observer on Friday.
The neo-JMB (Jama'atul Mujahideen Bangladesh) members were involved in the killing of professors, members of religious minorities and foreigners. It appears so. Initially, secular and atheist bloggers and writers were targeted.
Police have found out the militant roots after interrogating Abdus Sabur alias Saad alias Raju alias Samad alias Sujan. Sabur was arrested by Detective Branch (DB) of police for his alleged involvement in the killing of publisher Faisal Arefin Dipan.
Sabur is also one of the masterminds of the attempt on the life of publisher Ahmedur Rashid Tutul. Sabur has been named accused in both murder and attempt to murder cases.
Earlier on August 24, DB police had arrested the prime accused Moinul Hasan Shamim, alias Sifat, alias Samir, alias Imran from Cherag Ali Market under Tongi in Gazipur. The detainee was a 24- year old man from Sunamganj and former student of Madan Mohon College in Sylhet.
He is allegedly a member of Ansar Al Islam previously known as Ansarullah Bangla Team.
Dipan, owner of Jagriti Publications and son of Prof Abul Kasem Fazlul Huq of Dhaka University, was hacked to death in his office on the second floor of Aziz Supermarket at Shahbagh in the capital on October 31 in 2015. On the same day and almost at a similar time, attackers hacked Ahmed Rashid Tutul, 40, another publisher of books of slain blogger Avijit Roy.
Sabur disclosed to the court how Ansar Al Islam members were involved in the killing mission of Faisal Arefin Dipan and murder attempt on Ahmedur Rashid Tutul.
A university teacher killed on April 23 was not an atheist, but involved with cultural activities which many hard-line groups condemn as "un-Islamic." This view reflects increasing radicalisation in Bangladesh, a secular Muslim-majority country, where many show no sympathy for those perceived to be against their religion, even if that perception is without foundation.
The killing of a gay rights activist and his friend in Dhaka the day after the teacher was murdered is seen as further evidence that the militants are broadening their list of targets.
The attacks on Italian aid worker Cesare Tavella and Japanese farmer Kunio Hoshi last autumn were similar in style and reportedly claimed by IS.
But while the government says there is no organisational presence of IS in the country, many analysts say that matters little - because there are many local extremist groups which share the same ideology.
Four secular bloggers were hacked to death in Bangladesh last year, with each murder putting the spotlight on the government.
In October attackers attempted to slit the throat of a Christian pastor in Bangladesh's northern region. Police arrested five members of a banned Islamist group, Jamaat-ul Mujahideen, for the attempted murder. And a religious instructor in the Sufi strand of Islam - also known as a pir - was slaughtered at his home in Dhaka.
But despite the lengthening list of victims the police have made little progress relating to the investigations. In only one case - the murder of blogger Ahmed Rajib Haider in 2013 - a number people have been convicted.
But no one has been punished for the other killings. In fact in many cases the police have been unable to identify the culprits. For instance, it has been more than a year since writer Avijit Roy was hacked to death. But no one has been convicted.
