Meanwhile, a caller introducing himself as Joy and an associate of Bangla Bhai, threatened to kill Prof Munshi Mojibul Haque of Islamic History department if he did not pay Tk 40,000 as toll, adding that he would buy an AK47 rifle with the money.

Prof Haque informed the RU authorities, Rajshahi University Teachers' Association, Progressive Teachers' Association (PTA) and Motihar Police Station of the incident.

No class and examination was held at RU yesterday.

BCL brought out a procession and held a rally on the campus.

They demanded immediate arrest and exemplary punishment of the killers.

Students of economics department staged demonstration on the campus and submitted a memorandum to RU acting Vice-chancellor Prof KAM Shahadat Hossain Mondol.

They demanded arrest of the killers, declaration of December 24 as Prof Yunus Day, preserving his blood stained clothes and memorabilia at RU Martyrs' Memorial Archive, construction of a gate in front of Mamtaj Uddin Arts Building and naming it after Yunus and setting up of a memorial statue at the killing spot.

PTA in a meeting at Juberi Bhaban warned of an indefinite strike if the RU authorities do not conduct a proper probe into the teacher's killing.

They also demanded that the RU authorities and government ensure his family members' security and provide them with compensation.

They criticised RU authority's role after the murder and said they did not even officially express condolence after the tragic death.