A couple and their 22-year-old son were found dead in their home in West Bengal's Hooghly district on Thursday, an official said.
The victims, identified as Suresh Sharma, 58, Gayetri Sharma, 50, and their son Munna Lal Sharma, 22, are suspected to have been murdered in their hut in Daspara village, police said.
During preliminary investigation, police noticed a bullet injury on Suresh's body while multiple cut injuries were found on the head and shoulders of both Gayetri and Munna Lal.
K.K. Barui, sub-divisional police officer, Serampore in Hooghly district, said: "An unnatural death case has been initiated, we suspect that the victims have been murdered. But no clue was found."
The bodies were found lying in a pool of blood by police when they reached the spot Thursday morning after being alerted by the victims' neighbours.
Suresh was an employee of a private automobile company and took voluntary retirement in 2001.