Md Sumon Hossain Patwari, 20, was arrested here yesterday for his involvement in the attack on Ahmedur Rashid Chowdhury Tutul, the Dhaka Metropolitan Police said in a statement.
Tutul's publishing house 'Shuddhashar', whose publications were deemed blasphemous by extremists, had published writings of local secular writers.
He had also published books by a controversial Bangladeshi-American atheist writer Avijit Roy, who was murdered outside a book fair in Dhaka last year.
Ansar Al Islam, also known as Ansarullah, claimed responsibility for the attacks calling themselves as the Bangladeshi branch of al-Qaeda.
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Patwari "admitted to taking part in the attack and hitting the victim thrice with a meat cleaver," the statement said, adding the suspect has divulged important information about Ansarullah.
Police had placed a Tk 200,000 (USD 2556) bounty on his head last month.
His arrest comes amid a nationwide police crackdown to halt a spate of deadly attacks. Authorities have detained nearly 12,000 people. Some of those arrested were linked with outlawed Jamaatul Mujahedeen Bangladesh.