ULFA leader Anup Chetia was brought to Guwahati on Wednesday amid tight security.
Chetia was on November 11 extradited from Bangladesh to India. Central Bureau of Investigation (CBI) sleuths quizzed him in New Delhi.
Chetia was taken to the court of Chief Judicial Magistrate (CJM) of Kamrup in Guwahati.
Chetia, a founder of the ULFA, was arrested in Bangladesh in 1997 and had been languishing in different jails in that country since then.