Monu’s father Raju Rajak (top) and city SP Jayant Kant with the accused Kailash on Thursday. Pictures by Ranjeet Kumar Dey

A 12-year-old boy was allegedly sodomised and bludgeoned to death by a purported psychopath in the northwest part of the city late on Wednesday evening.

Within hours of the recovery of the boy’s body from the Bihar Vidyapeeth campus under the jurisdiction of Patliputra police station on Thursday morning, the culprit — identified as middle-aged Kailash alias Nepali — was arrested. Prima facie, he used to sodomise children before killing them.

Around 7am, Bihar Vidyapeeth campus residents spotted the body under thick foliage in one corner of the sprawling campus and alerted the police. In an hour, the body was identified to be that of Monu Kumar, a resident of Magadh Vihar Colony near Kurji Mor, roughly 3km away.

Monu, son of a washerman, Raju Rajak, left home around 6.30pm on Wednesday to fetch milk for the family but did not return. At 9.30pm, his father lodged a missing FIR with Digha police station.

Senior superintendent of police (SSP) Manu Maharaj told The Telegraph: “The boy’s head was smashed with a chunk of concrete. After recovering the body, we checked the records of missing cases and contacted Rajak. The father identified Monu by the clothes he was wearing. The body was sent for post-mortem. A forensic team and a sniffer dog were summoned. Scientific investigation helped us nab the killer so fast.”

Sources said Monu was a student of Class III of Prayag Niketan School in Kurji.

“During interrogation, Kailash confessed to have killed Monu and 11-year-old Rahul Kumar (also of Kurji), whose body was recovered on January 31 this year. Three men were arrested after Rahul’s family lodged a named FIR. Kailash is an alcoholic abandoned by his wife. He used to lure and sodomise children before killing them. Kailash lured Monu by promising to give him toffees and Rs 50. Kailash said he had enmity with Monu’s father. Further investigations are on,” the SSP added.

Sources said Kailash used to stay with his father in a makeshift tent on the Bihar Vidyapeeth campus.

Without much elucidation, the police said people’s co-operation helped them track Kailash. “The campus has thick foliage and trees and spreads over an area of more than 8km of which only a portion has human habitation. Residents tipped off the police about how Kailash used to roam around in the area in an inebriated state. He was finally tracked down. Bloodstains were found on his nails. Kailash led us to the murder weapon, a chunk of concrete,” another officer told The Telegraph.

During interrogation, Kailash reportedly told the police: “Monu’s father used to trouble me and snatch my money. So, I was angry and killed his son. Liquor made me more wild and angry. I didn’t know the earlier boy (Rahul) I killed.”

Sources said Kailash’s house was being constructed close to the Rajaks’.

“Rajak would be questioned on the enmity angle. The forensic team found the bloodstained chunk of concrete and a few pouches of liquor from the spot of the crime. The police will seek a speedy trial in this case. Further probe would be conducted from all angles,” the SSP said.