Late on Wednesday, 77-year-old Kolkata resident Arabinda De locked himself up in a bathroom in his house, and reportedly set himself on fire.

His body was recovered by fire department officials, who then informed the local police.

When officers from the Shakespeare Sarani police station visited the apartment, located in South Kolkata's upscale Robinson Street, on Thursday morning, they were unprepared for what awaited them.

Kolkata police found a 44-year-old man called Partha De living with the skeleton of his elder sister and those of the family’s two pet dogs.

The police found a 44-year-old man, the son of the deceased, living with the skeleton of his elder sister, and those of the family’s two pet dogs. The police later said the dogs had died in 2014.

The skeletons have been sent to the forensic laboratory. No arrests have been made in the case so far, but the police said they have questioned Partha De, the 44-year-old son of the deceased septuagenarian.

Police said Partha worked in a reputed IT firm before he left his job following his sister’s death.

His sister Debjani De, 47, who was an English teacher in a well-known private school in Kolkata, had died about six months ago.

She was extremely attached to the two pet dogs and could not cope after the pets died. She reportedly stopped eating and eventually died three months after losing the pets, police said.

As the police are gathering more information, more bizarre facts are being uncovered.

Police said they have found evidence that the three skeletons were being regularly "fed". The police have found various dry food items in the house.

Police also found that Partha used to listen to his sister’s voice and songs sung by her, which were previously recorded, in the flat all the time.

He had installed speakers in various corners of the house and believed that his sister was alive, the police said.

Police said that prima facie it appeared that Partha was mentally ill. Thus, he had refused to cremate his sister or even dispose of the corpses of the two pets.

Police said Partha also used to have heated altercations with his father Arabinda.

Partha De's father, 77-year-old Kolkata resident Arabinda De, locked himself up in a bathroom in his house and set himself on fire

The police have filed a case of an unnatural death.

“We are probing all aspects of the case. We have found Partha behaving suspiciously and that has raised our doubts,” said Kolkata Police deputy commissioner (south division) C Murlidhar.

He said they are consulting experts and would take Partha to a medical facility to assess him.