The elite force launched an operation in Sylhet city's Mendibag, Shahjalal Upashahar, Teroratan and suburban Tultikor and Srirampur areas at about 9 pm Sunday.

They cordoned the entire area and conducted a house to house search till early morning yesterday.

At about 3-30 am, Rab men caught JMB cadre Amanullah Rimon, 19, from the house of one Abdul Haque Kinu Miah, a businessman from Srirampur village in Sylhet Sadar upazila. Amanullah hailed from Khaghati village in Trishal upazila of Mymensingh district.

Abdul Haque told Rab men that he had extended lodging facilities to Amanullah a fortnight ago, knowing him to be a student. Amanullah appeared at the written test for admission to first year Honours class in Shahjalal University of Science & Technology (SUST) last week, Abdul Haque said.

Haider Ali Khan, Additional Police Super, Rab-9, Sylhet told The Daily Star that Amanullah admitted to interrogators that once he had links with Bangla Bhai.

Rab men suspected Amanullah to be an aide to Bangla Bhai after they got the address of his wife at RK Mission Road in Mymensingh town, a Rab official said.