The five said they murdered the blogger-architect on directions of a Islami Chhatra Shibir leader, the detectives said on Saturday. "They said killing Rajib was their Iman (religious) obligations," Islam said.



The five students were nabbed earlier in the morning with sharp weapons from raids in Dhaka.



The nabbed Faisal Bin Nayeem, 22, Maksudul Hassan, 26, Ehsanur Reza Roman, 23, Nayeem Sikder, 19, and Nasir Imtiaz, 22 were all students of various departments at the private North South University.



Detective Branch said they were picked up during raids at the capital's Khilgaon, Kakrail, Baridhara and Panthapath areas.



Two of those arrested were directly engaged in the murder yielding machete and knife. The three others assisted the two.



“One Shibir leader was involved in the murder plot,” Monirul Islam said , but did not mention names.



“He is a leader of the Islami Chatra Shibir at the North South University. He motivated the five to kill Rajib,” he said, quoting those arrested. “Efforts are on to capture the Shibir leader."



When asked why they killed Rajib, Monirul Islam they were carrying out what they believed was to their ‘Iman obligation’.



“A detailed interrogation could not be done… We will seek remand from court and then we hope to get details,” said the Detective Branch spokesperson.



Plot to murder Rajib was hatched several months back, he said. “He was being followed because of his facebook status updates… Perpetrators conducted dummy operations to prepare for the kill.



Of the detainees, Faisal lives in Dhaka’s Matuail, Maksud in Keraniganj, Roman is from Jhenaidah, Nayeem from Brahmanbaria and Nasir from Swandip of Chittagong.



Ahmed Rajib Haider was hacked to death in Pallabi of Dhaka in the night of Feb 15 - the tenth day of Shahbagh protests.



Relatives and friends blamed the Jamaat-e-Islami for the murder, saying he was killed for the blogs he wrote to bring 'war criminals' to justice.



Shahbagh's 'Ganajagaran Mancha' described Rajib as ‘the first martyr’ of the movement which seeks death for war criminals and a ban on Jamaat-e-Islami.



Home Minister Muhiuddin Khan Alamgir has said seven persons have already been nabbed in connection with Rajib's murder.



Detective police is now investigating into the case filed by Rajib’s father.



A blood stained laptop was found beside his body by the police. Some hairs were found his hand grip that police believes were those of the killers.



A Dhaka court has asked the Forensic Department Chief of Dhaka Medical College to arrange for DNA testing of the blood stains and the hairs.