The attackers, who the victim's flat mates said were a rival group of students led by an "outsider", dumped the body of Patna native Nishant Kiran, 22, in front of Bolpur block hospital.
Nishant, a third-year civil engineering student, had rented the ground floor of a two-storey house with four classmates from the Bengal Institute of Technology and Management, a private college about 8km from Santiniketan. The first floor of the house, in the Jambuni area of Bolpur, is vacant.
The 14-year-old institute, which has about 1,500 students, does not have a students' union but has been witnessing a battle for "control of the campus", Nishant's flat mates said.
"About 50 to 60 students, mostly seniors, have been trying to gain control of the campus," said Varun Singh, a third-year student who too is from Bihar.
Varun said the group that attacked Nishant around 2.30am belonged to the institute but was led by an "outsider, a third-year BA student from a college in Bolpur town". Varun named the "outsider" but the police were yet to verify the claim.
"They had asked us to join their group and beaten up some of us last week after we refused. I was hit on the head with a rod. We lodged a police complaint. Today, they killed our friend," Varun alleged.
Some local people said the "outsider" named by Varun was a known Trinamul activist.
Naresh Bauri, vice-chairman of the Trinamul-run Bolpur municipality, said: "He is a local youth and I know him, but Trinamul is not involved in the incident."
A senior officer said the police had got the names of eight suspected assailants, including the "outsider" named by Varun.
"We'll start a murder case as soon as the boy's father reaches Bolpur and lodges a formal complaint," the officer said, saying informally that any manhunt must wait till then.
Birbhum superintendent of police Mukesh Kumar did not take calls or reply to the text message this newspaper sent him.
Police sources said Nishant and his friends had last night held a birthday party for one of their juniors in the Jambuni flat.
"Nishant's flat mates told us he had had a drink too many and did not accompany them to Bolpur railway station to see off the junior. His friends locked the flat from outside before leaving for the station while Nishant slept," the officer said.
"While the four flat mates were returning home from the station, the rival group stopped them near the Bolpur bus stand and beat them with iron rods. They somehow escaped."
Corroborating the police version, one of Nishant's flat mates, Manish Kumar, said they had fled to a local hotel and rented a room.
"We checked into the hotel because they had threatened to beat us up at our flat," Manish said.
The police said the attackers appeared to have broken open the apartment's door and ransacked the rooms.
Neighbours said they had heard a lot of shouting from the ground floor of the Jambuni house in the dead of night.
Jiban Chatterjee, 54, a bus owner who lives two houses away, said: "Around 2.30am, there was suddenly a lot of shouting and the sound of something breaking. We did not step out as we thought the tenants were quarrelling among themselves."
Nishant's father, Ashok Sharma, who was on his way to Bolpur from Patna this evening, told The Telegraph over the phone that he had already spoken to his son's flat mates.
"They told me it was murder," he said. "I shall be reaching Santiniketan late tonight. I had thought a place near Santiniketan would be peaceful. Had I known my son would be murdered, I would never have sent him to this institute."
Amitava Choudhury, the registrar at Nishant's college, said: "We have informed the police. After this incident, we have decided that all students must stay at the hostel."
When this correspondent visited the Jambuni home of the "outsider", about 1km from the attack spot, he was not in.
His father, a mason, said: "My son has not returned home since last night. I don't know anything about the murder or his possible involvement."
His son's phone was switched off.
Doctors at Bolpur sub-divisional hospital, where Nishant's body was sent for post-mortem, said there were injuries in the legs and back.
"We have sent the viscera to Burdwan Medical College and Hospital for further investigations," a doctor said.
The Telegraph Calcutta.