A schoolgirl and a young man were allegedly tied together to a tree and abused at a higher-secondary school in Kashiani, Gopalganj, on 28 July.
The girl is an eighth-grade student at the institution.
She is 13 years old.
Local accounts alleged that the pair were taken to the school separately and then secured with a towel to a cedar tree on the grounds.
Those accounts said teachers, students and local residents were present while the pair faced physical and psychological abuse.
People at the scene recorded video, which was later circulated on social media.
The girl’s family and local people alleged that she ingested poison after the footage spread.
They said she was taken to a local sub-health centre and later referred to Gopalganj 250-bed General Hospital after her condition worsened.
The head teacher said he was not at the school on the day of the incident and would discuss possible action with the managing committee chair.
A man accused of involvement said he took the pair to the school to hand them over to guardians, but denied knowing that they had been tied up or abused.
Kashiani police station’s officer-in-charge said no complaint had been received.
He said police would investigate and take legal action if a complaint is filed.