Dhaka Superintendent of Police Maruf Hossain Sarder announced the decision after a meeting with the teachers and students on Friday.
He said police assured the teachers and students of steps to ensure their safety. "Patrols will be arranged in the neighbourhood. The authorities will discuss compensation for the family."
The institution's Principal Saiful Hasan said they have expelled the accused student, Ashraful Islam Jitu, 19, who was arrested on Wednesday. Witnesses said he attacked Utpal with a cricket stump at the institution on Jun 25. Utpal died in hospital two days later.
A lecturer of political science, Utpal was also the chairman of the institution's disciplinary committee. He used to correct students often through counselling and punishment.
The teacher had asked Jitu to refrain from hanging out with the female student at the premises of the institution some days ago, enraging Jitu, the Rapid Action Battalion said after arresting him. Jitu carried out the attack to show off "heroism" to the female student, the RAB said.
Police also arrested Jitu's father Ujjal Hossain and remanded both Ujjal and Jitu in custody.