Sleuths of the Special Investigation Team (StampIT) in Bangalore Saturday commenced a four-day interrogation of prime accused in the multi-crore fake stamp paper scam Abdul Karim Telgi, following his reported offer to expose "big sharks" in the scandal.

Armed with a special court order, the investigation agency formally took Telgi into custody from Parappana Agrahara jail on the city outskirts and took him for customary medical examination and later questioned him.

The special court earlier this week passed an order allowing Telgi to be handed to police custody for four days following an application by STAMPIT. It claimed that the prime accused needed to be interrogated following his reported offer to make a confessional statement.

Telgi was quoted as saying by his former lawyer Abdul Rehman that he would disclose the names of "big sharks" in the scandal.

The Karnataka High Court had Friday upheld the special court's order on Telgi, who had filed a petition questioning it.

According to government sources, Telgi was "highly secretive" and did not divulge any information to facilitate unearthing of any fresh facts, when he was interrogated for 10 days by STAMPIT in August last year.

He was then unwilling to share vital information on the exact extent of revenue earned through his illegal acts and their end usage, the sources said.