A top executive of the Maxis group was Monday questioned by the CBI in connection with alleged irregularities in spectrum allotment during the tenure of former Telecom Minister Dayanidhi Maran.Our correspondent quoting official sources said that Ralph Marshall, CEO of Astro which invested in Sun TV and also a Board member of Malaysia-based Maxis, appeared before the agency officials for clarifying on allegations that the company was favoured by the Minister in the takeover of Aircel.Agency sources said that CBI is looking into investments of Maxis in Sun TV which are alleged to have been done with Astro group. Besides, it is also looking into various aspects of takeover of Aircel by Maxis group.