The CBI team recorded the victim's statement and questioned her on various issues related to the crime, a spokesman of the agency said.
The team also inspected Nagar's official residence at Civil Lines, where he had allegedly raped the woman, the spokesman said.
CBI took over the investigation into the matter on October 9 and a day later it's team arrived in the city.
The agency had registered the case and got the case files from the state CID-CB, which had earlier registered the case against the former Dairy, Khadi and Rural Industries Minister.
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After registering the case, the police had referred the matter to the state's Crime Branch-CID as it involved a sitting MLA. The CB-CID had begun probing the charges.
The woman's statement was recorded and her clothes, which she wore on the day of the alleged crime, were sent for forensic examination.
CBI sources said Nagar would soon be questioned in connection with the case.