After a three-year long investigation, police are set to press charges against eight suspects, including sacked army major Syed Ziaul Haq as the mastermind, in the case filed for the murder of publisher Faisal Arefin Dipan.

All the suspects are members of banned militant outfit Ansar Al Islam, also known as Ansarullah Bangla Team (ABT), said Monirul Islam, chief of Counter Terrorism and Transnational Crime (CTTC) unit, yesterday, adding that Zia, the military wing commander of the outfit, planned the killing that was executed on October 31, 2015.

“We have already submitted the charge sheet, against eight people, to the home ministry for approval as the case was transferred under the Anti-Terrorism Act. We will submit it to the metropolitan magistrate court upon approval,” he said.

Six of the eight suspects have already been arrested under several cases, including the one for the murder of Dipan. They have also given confessional statements in court, admitting their involvement in the Dipan killing, Monirul said while talking to reporters at the Dhaka Metropolitan Police media centre.

The six arrestees are -- killing squad leader Moinul Hasan Shamim alias Samir alias Imran, 24; trainer Abdus Sabur alias Samad alias Sujon alias Raju, 23; top ABT operatives Khairul Islam alias Fahim alias Jishan, 24, Sheikh Abdullah, 27, Abu Siddiq Sohel, 34, and Mozammel Hossain alias Saimon, 25.

The CTTC officials came to know about Zia's involvement in the murder from the statement of Samir, who was arrested by police on August 26, 2016.

Zia and another suspect Akram Hossein alias Hasib are still on the run, the CTTC chief said.

Regarding the whereabouts of the two, Monirul said they were yet to identify their specific locations but warrants would be issued for their arrest once the charge sheet was submitted to court.

Apart from the eight, investigators also found the involvement of another suspect in Dipan's murder, but did not include his name in the charge sheet as they were not able to verify his actual identification and address.

“If we are able to verify the suspect's identity later, then we will submit a supplementary charge sheet,” said Monirul.

On October 31, 2015, Dipan of Jagriti Prakashani was murdered at his office in the capital's Shahbagh. His wife Dr Razia Rahman filed a murder case against unidentified assailants with Shahbagh Police Station.

The case was primarily filed under the penal code but after finding ABT's involvement, the investigators later transferred the case under the Anti-Terrorism Act, said Monirul. 

Just hours before the attack, publisher Ahmedur Rashid Tutul and his friends, bloggers Ranadipam Basu and Tareque Rahim, were injured in a machete attack at Tutul's publishing house “Shuddhoswar” in Lalmatia.

Both Tutul and Dipan were publishers of freethinking online activist writer-blogger Avijit Roy, who was hacked to death by assailants in the capital's TSC area on February 26, 2015.

According to investigators, ABT, said to be the Bangladesh branch of Al-Qaeda in the Indian Subcontinent (AQIS), carried out targeted attacks on secular writers, bloggers, publishers, freethinkers and LGBT rights activists between 2013 and 2016.