A senior police official said they were also talking to Bhardwaj's wife, who had been staying separately, and his sons to ascertain whether there was a property dispute and if he had any "enemies".
He said the police have questioned about a dozen people in connection with the murder. Police had also yesterday released a CCTV footage of the attackers at the Nitesh Kunj farmhouse where the incident took place.
The Skoda car in which they arrived at Bhardwaj's South Delhi farmhouse, is believed to have had a fake registration plate.
Bharadwaj, 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.
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He was gunned down by the trio who entered his farmhouse in Rajokri at 8:55 AM on the pretext of booking the place for a marriage, Delhi Police Commissioner Neeraj Kumar had told reporters here.
He had suffered bullet injuries on his chest and back and slumped bleeding heavily. He was rushed to Army's Research and Referral Hospital near Dhaula Kuan in south Delhi where he succumbed to the injuries.
Police have collected a video footage of the car in which the attackers came to the farmhouse located next to National Highway No 8 and used as a hospitality hub. They are also examining call detail records of Bhardwaj.