The arrestees are – Babul Chowdhury, 42, Md Tajul Islam, 32, and Sohel Mia, 23.

Among them, Babul is a cleaner at Habibullah Bahar College.

Detective Branch's Deputy Comissioner Md Masudur Rahman said Sohel was first arrested from Bangla Motor area on Wednesday morning.

Based on information provided by him Tajul was detained from Kakrail and Babul from Shantinagar, he said.

According to Rahman, Sohel Mia had opened a Facebook group named ‘Bangladesh Open University' on Oct 15.

There he stated that he could provide the 2013 HSC Bengali Second Paper question paper of BOU in the morning of the exam and posted his mobile number.

Following a complaint over the matter from the BOU authority, police swung into action and arrested Sohel, which led to the arrest of two others, said the DC.

“During preliminary interrogation Tajul told police Babul used to sell question papers to him,” he said.