RK Krishna Kumar, referred to in corporate circles as Ratan Tata's right-hand man, was questioned by the CBI in connection with the 2G spectrum scam. Mr Kumar is currently a director on the Tata Sons board and also heads Tata Realty, a part of the Tata Group. He was summoned to the CBI headquarters in Delhi along with his company's Managing Director, Sanjay Ubale.