Two other minor accused were found guilty and sent to a correctional home for three years by a juvenile court earlier this week, Nagaon Additional Superintendent of Police Ripul Das, who was part of the investigation team, said.
The girl, a class 5 student, was gang-raped and set on fire when she was alone at home in Dhaniabheti Lalung Gaon in Nagaon district on March 23.
The youths fled after the crime and the girl was rushed to the Guwahati Medical College Hospital where she succumbed to injuries the next day.
A case was filed in the Batadrava Police Station and the accused were arrested on charges of rape, house trespass, causing disappearance of evidence and murder under the IPC.
After a swift investigation, the police filed charge sheet on April 28 against eight persons.
The incident had led to widespread protests across the state with the Assam government announcing in the Assembly that it will bring in a stringent anti-rape law in the next session of the House.
The government also announced to recruit women Sub Inspectors through a special drive to have 30 per cent women in the police force.
Assam Chief Minister Sarbananda Sonowal had launched a toll free helpline '181-Sakhi' for women in distress and the Gauhati High Court approved the proposal for setting up exclusive fast track courts for trial of cases related to rape and murder of women and children in Assam.
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