Jahan died in a Dhaka hospital on April 10, five days after she was attacked at the Sonagazi Islamia Madrasa, sparking a nationwide outcry against sexual abuse and harassment.
She was taken by two classmates to the rooftop of the school where the accused asked her to withdraw the case against headmaster Dawla, according to investigator Banaj Kumar Majumder.
When she refused, a group of five people poured kerosene on her and set her on fire, he said.
Investigators had found involvement of 16 people in the murder and sought the death penalty for all of them.
The headmaster had plotted the killing from jail after he was arrested in late March when Jahan’s family filed a sexual harassment complaint against him, they said.
All the accused were present when the verdict was pronounced in the crowded court-room amid tight security, lawyer Farid Hazari said.
Some of the accused were seen shouting at the prosecution lawyers while the others broke down in tears hearing the verdict, he added.
The trial began in June and the court cross-examined 87 witnesses from both the defence and prosecution.
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