Jamshedpur, Dec. 14: Investigation into the murder of Indian Oil Corporation Ltd (IOCL) officer N.K. Ghosh received a setback with police declaring that the prime suspect is dead.

Kalimuddin Khan alias Kallu Mian, the man who was allegedly behind the murder of Ghosh, was killed by extremists in Rangaon under Tamar police station area in Ranchi district last week, police said.

The body of IOCL deputy sales manager Ghosh was found on National Highway 33 in Rangaon on March 26 this year. The body, which bore marks caused by cigarette butts, was tied up with a rope.

Ghosh had gone missing after he left his office on the evening of March 25. His car has still not been traced. A gold chain, finger rings and a cellphone belonging to Ghosh were not recovered either.

In August, the Tamar police arrested a gang of highway robbers, who were suspected to have murdered Ghosh. The police interrogated the leader of the gang ? Kallu Mian.

However, the police had to release him as they could not gather any evidence against him.

Subdivisional police officer (SDPO), Khunti, Madhusudan Bari, who is supervising the N.K. Ghosh murder case, today said the investigation might end without any conclusive finding.

Elaborating on the involvement of Kallu Mian in Ghosh?s murder, the SDPO said: ?After prolonged investigation, we arrested Kallu Mian on the basis of information that he had been committing robberies on the national highway between Chandil and Ranchi.?

Bari said they had to release Kallu as they did not have material evidence against him.

?Despite having enough reasons to believe that it was Kallu Mian and his gang who killed Ghosh, we had to release the suspect because we did not have material evidence. We wanted to wait till we could gather some strong evidence against him. But before we could do anything, the prime suspect was murdered.?

Bari said Kallu Mian had amassed a lot of property. Some extremist groups had targeted Kallu and asked him to pay a hefty amount as levy. When he refused, they killed him.

According to the SDPO, a beheaded body was found in Rangoan in Tamar about a week ago. The body was later identified as that of Kallu Mian.

He said relatives of the slain criminal had told the police that Kallu had been receiving threat calls from the rebels for refusing to pay up.