A police officer told the IANS on the condition of anonymity that they were raiding places in Haryana, Delhi and in the National Capital Reigion (NCR) for clues about the people who hired the shooters for Rs 1 crore.
"The shooters were given a contract of Rs 1 crore to eliminate Deepak Bhardwaj," said a police officer investigating the murder.
Police sources said that initially the shooters were given Rs.10 lakh to buy arms and a car to gain entry to Bhardwaj's farmhouse in south Delhi's Rajokri, where Bhardwaj was killed. The remaining amount was to be paid after the murder.
Police said two people were in contact with each other to find contract killers.
The source said that police have issued a Look Out Circular (LOC) for Rakesh Malik, who had approached the shooters and had given them the contract to kill Bhardwaj.
The hunt is on for Guru Swami, a resident of Jhajjar in Haryana, who had asked Malik to find contract killers.
The information came to light after the arrest of Rakesh alias Bhola, the owner of the Skoda car used in the murder and shooters Sunil Mann alias Sonu and Purushottam Rana alias Monu. The fourth arrested is Amit, who was driving the car at the time of the murder.
Amit was arrested Sunday from northwest Delhi's Jahangirpuri area while Rakesh had been taken in police custody last Friday after the recovery of the car from his possession.
The Crime Branch of Delhi Police arrested both the shooters - Sunil and Purushottam - in a dramatic way when they were about to surrender in Patiala House Court here Monday morning.
Purushottam was apprehended outside Patiala House Court complex and Sunil from inside the court as he managed to evade the police and entered Metropolitan Magistrate Prashant Sharma's court room to surrender.
Sunil was arrested after the judge refused to hear the matter and handed him over to the Crime Branch police.
Both the shooters were later handed over to South Delhi police, who are investigating the case.
Sunil, Purushottam and Amit were sent to 10 day' police custody by Patiala court Tuesday.
Police have questioned Bhardwaj's wife Ramesh Kumari, their sons and staff over the past few days.
Investigators are also looking into the role of an insider who might have tipped off the killers about the movement of Bhardwaj and the topography of the farmhouse.
Bhardwaj, a realtor and the richest candidate in the 2009 Lok Sabha elections with declared assets of over Rs 600 crore, was shot dead March 26 around 9 a.m. at his 35-acre farmhouse in Rajokri in south Delhi.
The killers entered the farmhouse on the pretext of meeting Bhardwaj. He was shot in the head and chest.