“We are interrogating Singla about the authority through whom he would have got the work done,” said a CBI official. The CBI has alleged that Kumar, a member (staff) of the railway board, the highest decision-making body of the railway ministry, wanted to become member (electrical), a post which is will become vacant on July 1. In addition, he also wanted additional charges of general manager (Western Railway) and signal and telecommunication. For the additional charges, Kumar, who was sent to CBI custody for four days by special judge Swarna Kanta Sharma, agreed for immediate payment of Rs. 2 crore. Kumar delivered a part payment of Rs. 90 lakh in Chandigarh to Singla and his associate Sandeep Goyal through his favoured railway contractors on the promise of helping them in the future. To get custody of Kumar, the CBI officials on Monday played a conversation of the accused in the chambers of Sharma. Investigators also showed the judge transcripts of some of the conversations. These conversations consist of 1,000 tapped phone calls in the case on which the CBI is relying to prove its case. “Mahesh Kumar was willing to pay crores immediately for additional charge of GM (Western Railway) as a GM has the authority to clear contract worth R200 crore,” said a CBI investigator.