Prasad has been convicted in one of these cases.
"Government's choice was wrong about this CBI director. You never know which side he will switch to. He is not a right person. We are gathering details about him," JD-U President Sharad Yadav told reporters here.
His remarks came on a day when Solicitor General Mohan Parasaran said that courts and not prosecutors should decide on dropping cases against the RJD supremo.
"I disagree with the Branch, HOZ and DOP. Since I do not agree with the DOP, let the matter be referred to the Solicitor General for his opinion on the legal issues raised in the petitions in all the three regular cases referred to in the comments of DOP," he had said on February 26.
The matter was examined by CBI at various levels in which the Director of Prosecution had opined that the present case did not attract provisions of Section 300(1) of CrPC and Article 20(2) of the Constitution.