According to the BBC, she gave a statement that was filmed by the officer in charge on his phone.
Appearing distressed in the footage — which was later leaked to local media — Nusrat tries to hide her face with her hand, while the policeman is heard calling the complaint "no big deal" and tells her to move her hands from her face.
Police arrested the headmaster, but a group of people gathered in the street demanding his release in a protest that was attended by local politicians.
On 6 April, 11 days after the alleged sexual assault, Nusrat went to her school to sit her exams, but a fellow student took her to the roof of the school — saying her mate was being beaten up.
"I tried to take my sister to school and tried to enter the premises, but I was stopped and wasn't allowed to enter," said Nusrat's brother, Mahmudul Hasan Noman, told the BBC.
"If I hadn't been stopped, something like this wouldn't have happened to my sister."
According to Nusrat's police statement — given shortly before she died — she reached the rooftop to find four or five people wearing burqas who surrounded her and allegedly pressured her to withdraw the case against the headmaster.
However, Nusrat refused and she was set on fire. When she arrived in hospital, doctors found burns covering 80 per cent of her body.
She recorded a statement on her brother's mobile phone in the ambulance.
"The teacher touched me, I will fight this crime till my last breath," she said.
Her death has sparked protests and thousands have used social media to express their anger.
Police have since arrested 15 people, seven of them allegedly involved in the murder. The headmaster himself remains in custody.
