Investigators have claimed that a “sleeper cell” of a militant outfit was behind the knife attack on Prof Muhammed Zafar Iqbal. 

At least four suspects were present near the campus of Shahjalal University of Science and Technology (SUST) just a day before the attack. They split after the incident and went to different districts, two senior police officials involved with the probe told The Daily Star yesterday.

It seemed the suspects were known to the detained attacker Foyzur Rahman, the officials said, citing some “technical clues”.

According to the investigators, Foyzur, a follower of salafism, had four Facebook accounts. He was self-radicalised online.

This correspondent visited one of the suspected accounts named Md Atiqur Bin Foyez and found various pro-militancy materials there.

Investigators suspects Foyzur might have links with Ansar Al Islam. He also might have used different encrypted cell phone applications for communicating with other members of the militant outfit.

“We have unearthed plans by Ansar Al Islam about carrying out recce regarding the movement of Prof Zafar Iqbal. But we are not sure whether Foyzur attacked the teacher following an organisational decision as his name was not found on the 'Ashkari Group' list,” said a top official from the counterterrorism unit.

The members of the “Ashkari Group” are trained to kill people, he said.

“We have a major breakthrough in the investigation and brought some suspects under surveillance,” Md Moniruzzaman, additional deputy inspector general of special affairs and intelligence of the Police Headquarters, told The Daily Star.

He said they were hoping for “something positive” soon.

Moniruzzaman said a number of the followers of salafism initially joined Jama'atul Mujahideen Bangladesh (JMB), another militant outfit, but later switched to Ansar Al Islam. “We need more time to verify some issues,” he added.

Prof Zafar Iqbal, a faculty member of Computer Science and Engineering department at SUST, came under the knife attack during a programme on the campus on Saturday.

Police with support of locals and university students arrested the attacker, Foyzur, along with a knife and a key of a bi-cycle. The bike was recovered at a garage near the campus later.

Footage of CCTVs installed on the campus shows Foyzur entering the area around 9:00am on the day of the incident. However, the bi-cycle was never seen in the footage later. Law enforcers were trying to find out how it reached the garage.

Police also claimed to have indentified two more outsiders, who were present on the stage along with the attacker just beside Prof Zafar Iqbal.

 Abdul Wahab Miah, additional deputy commissioner of Sylhet Metropolitan Police (SMP), said the outsiders, who were seen in some photos, would be detained soon for interrogation.

Meanwhile, law enforcers were examining a CPU, which was recovered from the house of Foyzur's uncle Fozlur Rahman. It is believed that the attacker had been using the computer.

Besides, police were also looking for a cell phone, which was reportedly used by Foyzur.

A top police official said they have already detained Foyzur's parents but they did not give any clue about Foyzur's militant activities. “We are now trying to catch his brothers, who are still on the run.”

SMP Commissioner Golam Kibria said they have detained another person for his suspected involvement in the incident.

Meanwhile, police yesterday detained a contractual security guard of SUST for interrogation. The detainee was identified as Khalikuzzaman of Dirai upazila in Sunamganj.

Prof Zahir Uddin Ahmed, proctor of the university, said the police requested the university authorities to grant police the custody of Khalikuzzaman for interrogation and the authorities agreed.

Abdul Wahab, ADC of SMP, said they detained a number of people to get clues about the sensational incident.

[Dwoha Chowdhury, our correspondent in Sylhet, contributed to this report.]