Police in Bangladesh have arrested two more suspected members of a banned group thought to be behind the slaying of secularist blogger Niloy Chottopadhay — the fourth such killing in the country this year.

Dhaka Metropolitan police official Mahbub Alam said Kausar Hossain Khan, 29, and Kamal Hossain Sardar, 29, were arrested late Thursday and are suspected members of the Ansarullah Bangla Team, which has been blamed for attacks on secularist bloggers and writers.

Two others, Saad-al-Nahin and Masud Rana, were arrested two weeks ago for suspected involvement in the killing of Chottopadhay, 28. Alam said the latest arrests were a result of interrogations of those two suspects.

Detective Mahbubur Rahman said that he sought authorization for police to hold Khan and Sardar for 10 days for interrogation but that magistrate Imdadul Haque approved five days.

Chottopadhay was hacked to death on Aug. 7. His wife, Asha Moni, filed a murder case against four unnamed people.

Police would not provide more details about Khan and Sardar but said they had been free on bail after being accused of attempted murder in an attack on another blogger, Asif Mohiuddin, two years ago. Mohiuddin has since fled to Germany.

Chottopadhay was an atheist blogger who went by the names Niloy Chowdhury and Niloy Neel online. His family and friends said he criticized religious radicals at home and abroad and sought police protection after receiving threats. Police asked him to leave the country for his safety, they said.

The United States has expressed concern over the killing, and the United Nations called for Bangladeshi authorities to ensure accountability and prevent such violence. U.N. Special Rapporteur Heiner Bielefeldt is to visit Bangladesh starting Monday to assess the state of freedom of religion and belief there.

In February, Bangladeshi-American blogger Avijit Roy was hacked to death on the Dhaka University campus while walking with his wife. Two other bloggers were attacked and killed in March and April, one in Dhaka and one in the northeastern city of Sylhet.

Three suspects, including a Bangladeshi-born British citizen, have been arrested in connection with Roy’s death, but investigations into those cases have had no major breakthroughs.

News wires