On Friday, the 35-year-old victim's voce sample was recorded by the Criminal Investigation Department (CID) Crime Branch.
The officers also recorded the statement of the woman and her son at their residence.
Nagar has already been suspended from the Congress party.
Nagar had resurfaced on Sept 28 for medical tests in connection with the case at a hospital in Jaipur after evading it for more than a week.
The Rajasthan government on Sept 28 had recommended a Central Bureau of Investigation (CBI) probe into the rape case which involved Nagar.
Nagar resigned from the state cabinet on Sept 19 but claimed innocence.
"The allegations are baseless and false. That woman is known here for doing this with every other man," said Nagar.
"Earlier also, that woman had taken money from prominent people and asked for jobs by blackmailing them," he said.
The woman alleged that Nagar called her to his house on Sept 11 and then beat her up before raping her.
The minister has been booked under sections 376 (rape) and 323 (voluntarily causing hurt) of the Indian Penal Code (IPC).
On Sept 13, the woman recorded her statement before metropolitan magistrate Pradeep Modi.
--IBNS (Posted on 05-10-2013)