Chief Judicial Magistrate of Cachar district sent the prime accused Dibyendu Kar, a lawyer, to police custody.
Kar was arrested by police on the night of August 15-16 from Borkhola, about 25 kms from here while a manhunt is on for three others named in the incident.
Several prominent organisations and NGOs had staged protests in the past few days demanding the arrest of the four accused in the alleged gang rape of the Silchar Womens college student.
The girl, who hails from Uzan Bazaar area of Guwahati, was forcibly picked by four persons and taken to the remote Kumbhirgram airport road and allegedly gang-raped.
The accused had also threatened of dire consequences if she went to the police. The girl had, however, filed an FIR at the Silchar police station on August 14 after her mother and sister arrived from Guwahati.
Meanwhile, Cachar District Bar Association has expelled Kar.
