Sources said Ramesh Kumari, who was staying separately, was quizzed a day after police recovered the car allegedly used by the killers in Haryana.
Police had yesterday picked up four men, who were suspected to have provided illegal arms to the assailants involved in the killing of the 62-year-old politician.
Investigators suspect the attackers were from Sonepat, going by the way in which the operation was carried out.
Bhardwaj, the richest candidate in the 2009 Lok Sabha polls with declared assets of over Rs 600 crore, was fired upon from point blank range by three men who fled after the incident on Tuesday.