Following the man's complaint, police registered a case under IPC Section 302 (murder).
The post-mortem was performed in the presence of Suprintendent of police M Kannamma and the entire process was video graped.
The SP said arrests if any would be made after the 10 day Pongal holidays for the school.
The boy committed suicide yesterday in his hostel room after he was suspended for allegedly misbehaving with a lady teacher during a New Year Party thrown by the school.
Yesterday he had informed his classmates that he was going to the bathroom, but did not return following which a search was launched. He was found hanging in his room.
His agitaged classmates then ransacked the office and broke windowpanes in many classroom.