Purulia SP C Sudhakar said 42-year-old Arun Mahato, his wife Lakshmi mahato and two-year-old son were killed in front of their parents.
The aged parents were so traumatised by the brutal killing that they lost their voice and were admitted to a hospital nearby for treatment.
The SP said no arrest had been made yet as the police was waiting for the parents' voice to restore to know the details.
Meanwhile, the police suspects that contract killers had been hired for the job and family dispute was the reason for the murders.
