Buta Singh had said he would cooperate with the CBI but accused the agency of plotting a 'political conspiracy' against him by 'framing' his son.

CBI sources now say they are unlikely to question Buta Singh because they do not have anything concrete suggesting his involvement in the matter.

'We don't have any recorded conversation between Buta Singh and his son suggesting the former was aware of the conspiracy. We recorded telephonic conversation between Sweety Singh and others,' the source added.

The CBI officers feel they have enough material evidence and witnesses to prove their case against Sweety Singh in the court.

The agency is now planning to question Sweety Singh's father-in-law, whose mobile phone was used to make calls to hawala operators and other accused, according to the investigators.

The corruption case against Sweety Singh follows a complaint from Patil, who alleged that Sweety Singh demanded a bribe of Rs.3 crore to facilitate the withdrawal of the case filed against Patil by a group of conservancy workers.

Patil is a garbage collection contractor with the Nashik Municipal Corporation. Some 100 of his employees complained he was not paying their wages and had also taken a bank loan of Rs.10 crore in their name. Now the bank was asking them to cough up the money.