Sources say that in its next chargesheet, to be filed within the next two weeks, the agency will say that Ishrat was "an innocent college girl", presenting a boldface controversy for chief minister Narendra Modi, who is in the running for Prime Minister.
The BJP has already alleged that the ruling Congress, unable to politically combat Mr Modi's surging popularity, is using the CBI to question his credentials and mar his reputation as the national elections approach.
In its first chargesheet presented in a Gujarat court in July, the CBI accused seven senior policemen of murdering Ishrat and her three male companions in "cold blood" and of planting an AK-56 at the scene of the shooting to portray the victims as terrorists.
One of those officers, DG Vanzara, who was then Deputy Commissioner of the Amedabad Crime Branch, wrote an explosive letter to Mr Modi from jail recently.
He alleged that Mr Modi's close aide, Amit Shah, who was Home Minister when Ishrat was killed, was aware of the police's actions, but that the cops have now been betrayed by a weak state government. The senior officer repeated the defense that his team was trying to fight Pakistani terrorists.
The CBI says that Mr Vanazara has refused to cooperate and share more details of the accusations he made in his note against Mr Shah. So far, the CBI has not interrogated Mr Shah, or linked either him or Mr Modi to its investigation.
