Rajya Sabha MP Kapil Sibal on Friday congratulated the previous UPA government and the current dispensation over Mumbai attacks mastermind Tahawwur Hussain Rana's extradition and expressed confidence that it will now become clear who all from Pakistan's establishment were involved.

The National Investigation Agency (NIA) on Friday began Rana's questioning here to unravel the larger conspiracy behind the deadly terror strikes of 2008, official sources said.