Police have made no arrests more than four days after Chandranath Rath was shot dead near his Madhyamgram home. Investigators believe the killing was a planned operation, with clues pointing to outside shooters and local support.

Chandranath Rath, a close aide of West Bengal's new Chief Minister Suvendu Adhikari, was shot dead on a busy road on Wednesday.

Three people have been detained in connection with the killing and are being questioned, police said, adding that no arrests have been made so far.