The mutilated body of an unidentified youth was found in Madavara on Tumakuru Road on Thursday.
Police said that the body belongs to a man, aged around 25 years. He seems to have been bludgeoned to death.
The assailants crushed the head of the man with a boulder and set fire to the head to conceal his identity. Passers-by noticed the head and informed police.
The police have taken up a case of murder and are verifying the missing cases to ascertain the identity.