An FCI employee, his wife and the couple’s youngest son were found dead with multiple injuries in their two-storeyed house at Nabanagar in Howrah’s Mourigram on Thursday evening.

The body of the man’s sister-in-law Krishna Basu, 58, was found in her adjacent single-storey house.

Police sources said the bodies of Biswanath Singha, 55, his 48-year-old wife, Kalpana, and son Sumit, 24, were in various stages of decomposition. The killing probably took place on May 14.

Biswanath’s elder son Suman, a 26-year-old student of Amity University in Lucknow, discovered the murders. He had arrived from Lucknow around 5.30 pm to spend summer holidays at home.

“Suman called the neighbours when his family didn’t respond to his knocks on the door. The door was locked from inside. He went to his aunt’s house, where also he didn’t get any response. There was foul smell emanating from the houses,” an officer said.

The officer said it was intriguing that the doors were locked from inside. “How did the killer or killers escape? We are working on clues” he said.

He said that a pair of bloodstained scissors was found lying near Kalpana’s body.

The officer said cooked food, which has gone stale, was found on the dining table.