Kolkata, Oct 30 : In the mysterious death of the 11-year-old niece of Sanjay Roy, the convict in the R. G. Kar case, a murder case has been filed against his sister and brother-in-law, said the police on Thursday.

According to police sources, the deceased minor's grandmother, Pratima Singh, who is a resident of Vidyasagar Colony in south Kolkata's Alipore area, could not accept the untimely death of her granddaughter.

She filed a complaint against her son, Bhola Singh and daughter-in-law, Pooja Singh, at the Alipore police station in connection with the murder of her granddaughter.

However, apart from the grandmother, some residents of Vidyasagar Colony on D.L. Khan Road in Alipore have also filed a written complaint against Bhola and Pooja for the murder of their daughter.

A police official said that since the complaint is of murder, a case under the relevant sections has been registered against Bhola Singh and Pooja Singh.

"The investigation is being carried out with great seriousness. We are looking into all possible angles," said a senior officer of Kolkata Police.

According to the police, Sanjoy Roy's niece (11) was found hanging inside a cupboard in Vidyasagar Colony on October 19.

She was rushed to SSKM Hospital, where she was undergoing treatment. On October 20, the sixth-grade student died.

It is learnt that no one was at home at the time of the incident.

The police came to know that the deceased's own mother and Sanjoy Roy's sister had committed suicide a few years ago. After that, Roy's father married off another daughter, Pooja, to Bhola Singh.

Pooja had gone out to buy firecrackers on Sunday evening when the incident took place.

Residents of the area told the police that domestic quarrels were frequent in Bhola's house.

Meanwhile, the preliminary post-mortem examination report of the 11-year-old indicated that she died by suicide.

The autopsy report indicated suicide after seeing evidence, including marks of hanging on her neck. However, neighbours alleged that the father and stepmother killed the minor.

Pratima Singh alleged that her granddaughter often came to her secretly and complained about her father and stepmother beating her.

She alleged that Pooja often thrashed her stepdaughter. Even before Kali Puja and Diwali, the father had beaten up the minor with a belt.

Her grandmother and neighbours alleged that the girl died due to the torture of her stepmother and father.

Based on her complaint, the police have now registered a case. However, no one has been arrested so far.

/IANS