CBI has summoned Managing Director of IDS Infotech Partap K Aggarwal and CEO of Aeromatrix Info Solutions Pvt. Ltd Praveen Bakshi for probing in connection with the Agusta helicopter deal. Their firms are suspected to be used in routing alleged bribe money in India. Former Air Force Chief S P Tyagi has also been summoned tomorrow again for a fresh round of questioning.<br/><br/>CBI yesterday questioned Mr. Tyagi's cousins, besides advocate Gautam Khaitan for nearly eight hours asking exhaustively about finances, firms established by them and their relations with European middlemen in helicopter deal.