The incident came to light this morning when Lalapan, his wife Prasanna, a nurse in a government hospital, and their son Praveen, were found dead by some people who had come to collect their clothes from the laundry adjacent to the victim's house.
Acid was poured on the three as they were bashed with an axe and electrocuted at Parambuzhayil in this district, police said.
Police said they suspect involvement of some migrant labourers, who were working in the laundry, behind the crime.