The CBI on Monday interrogated Vectra chief Ravi Rishi for the third time in a week in connection with the Tatra truck deal. The agency will next question defence PSU BEML boss VRS Natarajan in course of the ongoing probe. Rishi turned up at the agency headquarters at 2 pm and was grilled till the evening during which he is learnt to have denied the allegations levelled against him. The investigators, however, confronted him with documents pertaining to the deal between Vectra and BEML for supply of the all terrain Tatra trucks to the Army.