The body of the unidentified man, aged around 30 years, was found with his throat slit at Kianga village in Mathili area, Superintendent of Police Akhileswar Singh said.
A poster left near the body by the killers stated that the man had to pay the price for being an informer of the police, he said.
Written in Hindi, the poster carried the name of Kanker division of CPI (Maoist), police said adding efforts were on to ascertain the identity of the victim, who was believed to be an outsider.