Police said accused teacher Nezma Khatoon, hailing from Madhya Pradesh, was angry over victim Vinay Kumar's alleged friendship with her daughter.
Vinay was found murdered brutally on Thursday near the teachers' hostel at the Saffaire International school here. Police sources said the boy suffered head injuries inflicted by blunt objects and his liver too was damaged due to severe beating.
Ranchi Police had questioned seven schoolteachers, security guards and others in the case.
Meanwhile, the Jharkhand High Court on Wednesday issued notice to police, school and state government and sought details in the case along with the post-mortem report, Ranchi Abhibhavak Sangh general secretary Ajay Rai, who moved the high court on behalf of the association, said here.
The association on Wednesday also called for a shutdown in Ranchi and Khuti district, which evoked a mixed response. Majority of schools in Ranchi were closed.
The association on Tuesday filed a public interest litigation in the high court to demand a CBI probe into the student's murder.
"We have filed a PIL in the high court for a Central Bureau of Investigation probe since we are not satisfied with police investigation. Even the boy's parents are not satisfied. We want justice for the murdered student and his parents," Rai said on Tuesday.