Partho De on Monday told doctors that his father Arabindo had come to know about his sister Debjani's death around mid-April when the 75-year-old had walked into the son's room on the second floor of the Robinson Street house.

"One day my father stepped into my room, saw something and then an object fell from his hands. At that moment I realised he had come to know about didi's death," a doctor at Calcutta Pavlov Hospital quoted Partho as saying.

Partho was admitted to the hospital for the mentally ill on Thursday evening, following the death of his father and the discovery of skeletons believed to be that of Debjani and two dogs in his room.

Debjani had apparently starved herself to death in December. Partho said he had been living with her skeleton as he couldn't bear to part with his sister.

He also told the doctors his father had set himself on fire after locking himself in the bathroom. "I alerted the guards downstairs and also the fire station," a doctor quoted him as saying.

Doctors said he spoke slowly and chose his words carefully. "He spoke on different subjects, often in English. He came across as one possessing a sharp mind," said a doctor.

The bulk of the conversation - in two phases of an hour each - was on Arabindo and Debjani.

Sitting in a room on the ground floor of the male ward, Partho is said to have told the doctors that his sister had "reached such spiritual heights over the years" that their father "couldn't keep up" with her.

"She became detached from the material world and wanted to transcend into another world. That's why she started fasting and I didn't want to come in her way," a doctor quoted De as saying.

"Partho said he is a religious person, too. He has a very personal religious belief, which is a mix of Hinduism and Christianity. He said he thinks Hinduism is too cluttered and unorganised, while Christianity is more disciplined."

Partho also apparently told the doctors that some of their family members were responsible for the death of his mother Arati, who was a cancer patient. "He feels his grandmother, along with his uncle and aunt, had resorted to some black magic to hasten his mother's death. That is why he said he hates his uncle and aunt," a doctor said.

A team from Shakespeare Sarani police station asked the hospital authorities on Monday evening whether Partho was fit for interrogation. They also wanted to know whether he could be shifted to the Institute of Psychiatry at SSKM Hospital.

The talks continued for 30-40 minutes but the police were denied permission till late in the evening to question Partho or shift him to SSKM.

A senior member of the team treating Partho said he appeared tired after the long session earlier in the day and was not in a position to be questioned or shifted.

One doctor who has seen Partho said he could be suffering from schizophrenia and delusion, which means it is still too early to take all his statements seriously.

"He is clear on certain things, though. For instance, asked whether he wanted to know what was being written about him in the media, he said those were 'all trash'," the doctor said. "He told us he would only speak to cops if a nun from the Mother House was around."

In the first phase of the conversation, Partho spoke to a team of psychiatrists who are members of the medical board treating him. In the second phase, the team was joined by doctors from other fields, such as medicine and dermatology.

Doctors said in each session they were trying to assess how the "patient" was responding to treatment, which includes a dose of Olanzapine, an anti-psychotic drug used for treating schizophrenia.

"He has responded very well and is doing fine. We have noticed that he is in a far better mental state than he was before," said Ganesh Prasad, the superintendent of Calcutta Pavlov Hospital.

Hospital sources said Partho, lodged in a 8ftX10ft room that opens to a ward with around 50 patients, looked much fresher than what he was last Thursday night. The initial resistance to food is gone, and so is his habit of offering two biscuits to his sister everyday before lunch.

He has started taking showers and is having the hospital's regular lunch.

Partho has been sleeping for long hours. While awake, he would mostly immerse himself in Tagore's Gitanjali and would at times speak to Group D employees of the hospital.

"He had asked for bottled drinking water and a ceiling fan. Both his requests have been complied with," a hospital official said.