At least 11 persons, mostly madrasa students, were involved in the murder of online activist Oyasiqur Rahman Babu, detectives say.

Five of them were trained at a two-room apartment of a five-storey building at Nayanagar in the capital's Jatrabari. They were recruited by five different persons, including their coordinator known to them as Mashul alias Masum.

DB officials learnt these after interrogating Zikrullah and Ariftil Islam, who were caught by people and handed over to the police soon after Oyasiqur, 27, was hacked to death in the capital's Tejgaon Industrial area around 9:00am on March 30.

Tayes Rahman, son of the building owner, told The Daily Star that a person introducing himself as Iqbal rented the flat on January 1. "Iqbal told us that four or five students would live here and take tuition on English language."

"They hardly went outside the flat. I saw Iqbal once or twice", he said, adding "Iqbal, who is tall, healthy and black, claimed to be a university student."

They lived their till March 25.

Iqbal, believed to be one of their mentor and financier, used to pay the rent. DB officials learnt that another person, who could be a trainer, often visited the apartment.

Deputy Commissioner of Detective Branch Sheikh Nazmul Alam told this correspondent that they were questioning the arrestees also about the killing of writer-blogger Avijit Roy.

A day after the February 26 murder of Avijit, the group members asked a trainer about it In reply, the person said it was none of their business and that they need not focus on anything outside their task.

"More information will be found, if Iqbal, the coordinator who is known to them as Mashul alias Masum, can be arrested," said the deputy commissioner.

Zikrullah, Ariftil and three others -Abu Taher, Abrar and Saiful Islam -started living at the apartment. They were yet to know their target when their training began but.

Given the particulars of Oyasiqur onMarch 15,they went on a recce to his house and office and gathered information on his daily routine, said DB officials.

Before renting the house, the group had a meeting in Mirpur, an investigator told The Daily Star. “The five were recruited for killing atheist bloggers in December last year by five different persons."

The members of the group knew each other only by name, he added.

The first attempt to kill Oyasiqur was made on March 24. As per the plan, they left the house one after another with cleavers in their haversacks.

Among them, Saifullah had a pistol with six bullets. But police caught him near Jatrabari Ideal High School. Abrar, who saw it from far, ran away from the. The mission failed.

Zikrullah, Ariftil and Taher went

back to the apartment and Iqbal them assigned them to carry out the mission.

Saifullah had given different versions at different times on remand after his arrest since March 24. But when he was brought before Zikrullah and Ariful, he admitted to receiving training with them, said DB officials.

After their arrest, Zikrullah and Arifiil told police that they along with Taher, who managed to flee, had hacked Oyasiqur.