The class 10 student whose body was found in the washroom of a reputed school here had committed suicide, the post-mortem examination report revealed on Saturday.
The girl who was found with a plastic bag wrapped around her face and injury marks on her left wrist on Friday died of asphyxiation, the police said.
'I quit': Teenage girl found dead in Kolkata school washroom with wrist slit, plastic packet tied around face
However, the police said they are looking into every aspect of the case before closing the investigation while forensic experts have collected evidence from the spot and analysed Friday's CCTV footage obtained from the school.
The girl's mother reportedly told the police that she had attempted to kill herself earlier as well.
The authorities of the school at Ranikuthi in south Kolkata had informed the police about the girl, a topper of her class, after she was found in the washroom. She was taken to a nearby hospital where doctors declared her "brought dead".
There were some marks of self-inflicted injuries on her left wrist as well. But the doctors said they were not the cause of her death, a police officer said.
A few pages of hand-written notes were also found near the girl's body and they were sent to an expert who confirmed that the handwriting was that of the girl.
Quoting the note, police sources said, the girl was under immense stress as she wanted to get admission at the Indian Statistical Institute and had not slept properly for the last three months.
The note also revealed that she was unhappy with the frequent interference of her parents in her personal matters.
She had dreams of travelling to Spain by train, to reach London in a two-wheeler and reach the Everest base camp, according to the note.
While the National Commission for Protection of Child Rights sought a report of the incident, a team of its state counterpart talked to the parents of the girl and school authorities on Saturday.