Rai is the director-cum-principal of the VR College in Vaishali district which is being investigated in the case.
According to police officials, Rai, who has been absconding, surrendered near his college in Vaishali and the police arrested him. Police will produce him in the local court by evening.
In the last 48 hours police had raided several places but failed to track Rai.
Meanwhile, former Chairman of Bihar School Examination Board Lalkeshwar Prasad Singh is still absconding, police said. Singh is a key accused in the case and has gone underground after resigning from the Board.
Earlier on Friday, five accused arrested in the case were remanded to 14 days’ judicial custody by a local court in Patna.