Kolkata Police has registered a case of unnatural death in connection with the sudden demise of singer Krishnakumar Kunnath, popularly known as KK, on Tuesday night.

The singer fell ill while performing at an event in Kolkata on May 31 and was brought to the CMRI hospital, where he was declared dead. The case has been registered at the New Market police station where the police are awaiting the late singer's family.