The investigators are tightlipped about how many suspects have been picked up for questioning from different areas of Habiganj, Sylhet and the carnage spot of Baidderbazar's Bangaon village, but they say they have not yet arrested anyone. Sources said they have detained "several" suspects.

They said that the information obtained through questioning the suspects and witnesses yielded a lot of important clues, although this information needed thorough verification.

Investigators are also tightlipped about clues relating to Thursday's grenade attack, which killed 5, including former finance minister SAMS Kibria. "We don't want the culprits to be aware of what we know and get away before we can take action," said an official.

"We have come to know that there is one or more persons who actually saw the assailants throwing the grenade," said an investigation team source.

Some of the detained persons were released after questioning.

Habiganj Chhatra Shibir former president Nurunnabi Uzzal, who was arrested Sunday, was released yesterday. However Sylhet's Jatiyatabadi Chhatra Dal (JCD) leader Kala Jamal still remains in detention.

Investigators say they have the impression that there were five to six people involved in the attack, who were roaming around the Baidderbazar area much before the Kibria rally ended Thursday. They had tea at a local tea stall, where some local people accompanied them. "We have strong support against our assumption that the assailants used a motorbike in this operation," said an official.

Meanwhile the case of the grenade attack and murder has been assigned to the Central Intelligence Department (CID). Munshi Atikur Rahman, CID's Senior Assistant Superintendent of Police (ASP), has started an investigation in Habiganj. "I can just say that I have seen the diaries and documents," he told The Daily Star.

The new officer in charge of Habiganj Sadar thana Safiuzzaman-- who is also the investigation officer (IO) of another case filed under the Explosive Substance Acttold The Daily Star, "I am confident the culprits of this case will be exposed."

Explaining the reasons for his confidence, Safiuzzaman noted, "Former finance minister Kibria did not have political or personal enmity with anyone. That's why we hope that all political parties will cooperate with the investigation."

AKM Mahfuzul Haq, Deputy Inspector General (DIG) of Sylhet range, who heads the high-level investigation committee of the government, points out, "We have good progress in the investigation. But in its interest we can not say anything about it."

"We don't have any arrests yetbut we are questioning (people)," he said without specifying how many persons are being questioned. "We are also verifying the information coming out from the questionings. We will do this till we are satisfied."

Meanwhile the Habiganj District Lawyers Association is also investigating the carnage. Khalekuzzaman Chowdhury, the association's president, is heading an eleven-member team that visited the carnage site yesterday.

The Habiganj district Awami League, 11-Party, JSD and Nap are jointly organising a condolence meeting for Kibria in Habiganj town today at 2 pm, at which central party leaders will participate.

Sylhet DIG said the police have taken all necessary security measures. Participants will be searched before they enter the meeting at Shirishtala, he said.