Rapid Action Battalion (RAB) on Monday arrested Shafiur Rahman Farabi, prime suspect in writer and blogger Avijit Roy murder, from capital's Jatrabari area.
Rumman Mahmud, deputy director of the legal and media wing of RAB, said they arrested Farabi from Jatrabari Bus Stand area around 5:30am.
On February 26, Avijit Roy, was hacked to death and his wife injured in a criminal attack near the TSC at Dhaka University.
Avijit's father Ajoy Roy, a former professor of physics Department at DU, filed a murder case with Shahbagh Police Station accusing unknown assailants.
UNB adds, Farabi reportedly issued death threats to Avijit on social network Facebook for his critical take on radical interpretation of Islamic teachings on several occasions.
Earlier in 2013, Farabi was arrested in a case for issuing death threats to an Imam with death for administering a burial ceremony for slain blogger Ahmed Rajib Haider. Later, Farabi got temporary bail in the case.