Sifat, who also goes by the aliases Shamim and Moinul Islam, had a Tk 200,000 bounty on his head.
He is one of the six militants for whom three months ago police had announced a total bounty of Tk 1.8 million for information leading to their arrest. Police believe the six were involved in the murder of bloggers, secular writers and Dipan.
The media will be briefed on the matter later at a press conference, he said.
On Oct 31 afternoon last year, publisher Dipan was found hacked to death in his Jagriti Prokashony office at Shahbagh's Aziz Super Market in Dhaka.
Prior to Dipan’s murder on the same day, Ahmedur Rashid Tutul, owner of Suddhaswar, another publishing house, and the secular writers Tarek Rahim and Ranadipam Basu came under vicious attack at Tutul's office at Lalmatia.
The three, however, survived the attack with critical injuries.
Both Tutul and Dipan had published books by the secular writer-blogger Avijit Roy, who was killed in similar fashion in February last year.
Dipan was the only son of the writer and Dhaka University teacher Abul Kasem Fazlul Haque.
Before and after Avijit Roy's murder, several other bloggers, writers and Ganajagaran Mancha activists were brutally murdered by suspected militants in the past several years.
In May, Dhaka Metropolitan Police released the photos and names of six youths who they said were operatives of the banned militant group Ansarullah Bangla Team, and announced rewards for their arrests.
Tk 500,000 was offered for clues leading to the arrest of each of two militants – Shariful aka Sharif aka Saleh aka Arif aka Hadi, and Selim aka Iqbal aka Mamun aka Hadi-2.
Tk 200,000 each would be given for information leading to the arrest of any of the remaining militants.
They are Sifat, Abdus Sabur aka Sujon aka Raju aka Salman aka Saad, Shihab aka Sumon aka Saiful, and Sajjad aka Sajib aka Siam aka Shams.