Bangladesh police say they have arrested a leading suspect behind last year's killing of an American-Bangladeshi writer and blogger amid an ongoing crackdown against radicals blamed for violent attacks on foreigners, liberals and minorities in the country.

Police say Moinul Islam Shamim was arrested late Tuesday from Tongi area just outside the Bangladesh capital.

Police officer Monirul Islam says Shamim is a key organizer of the banned group Ansarullah Bangla Team, which is blamed for attacks on atheist bloggers and online activists.

American-Bangladeshi Faisal Arefin Deepan was killed Oct. 31 in his office in Dhaka. A similar attack on the same day left another publisher, Ahmed Rashid Tutul, and his two friends seriously injured.