Deepak Sharma, 34, was taken into custody Saturday from Sector 5 in Pushp Vihar in south Delhi. Police recovered Rs.2.36 crore of the Rs.5.25 crore that was looted from the van carrying cash belonging to ICICI Bank.
"Deepak Sharma is the mastermind of the heist," said Joint Commissioner of Police Vivek Gogia.
Co-accused Mukesh and Tekram were arrested for helping Deepak in hiding Rs.85.85 lakh in a house, police said. A hunt is on for four others involved in the crime.
A 9 mm pistol, two magazines and Rs.1.51 crore were recovered from Deepak, police said, adding that he was involved in three other robberies.
Deepak has been sent to 14 days judicial custody while Mukesh and Tekram are still in police custody for questioning.
Investigators pointed to an insider's role in the crime as the robbers were waiting for the cash van to arrive before striking.
"We formed more than 25 teams, including teams of the crime branch and special units," Gogia said.
Gogia said that around 1.13 p.m. Friday police received a call of a gunshot from south Delhi's Defence Colony.
Anil Kumar, 27, the driver of the cash van, a radio taxi (DL 1 RT 2088), revealed that some armed men in a white car, bearing registration number HR 26 AQ 0051, blocked the cash van's way near a petrol pump in Defence Colony around 1 p.m.
"The assailants pulled out Anil, Ashok Kumar Singh, the cash custodian, and two guards. Guard Munne Singh, 40, was shot in the chest by the accused. The other guard was Ajab Singh. The accused fled with the van leaving their car behind. Mobile phones and weapons were also taken away by the accused," said Gogia.
Munne Singh was rushed to the All India Institute of Medical Sciences where he succumbed to his injuries.
Gogia praised residents who helped find the cash van near Zakaria park in south Delhi's Hauz Rani neighbourhood.
"The two weapons of the guards were recovered from the van," Gogia said.
Sketches of the accused were prepared with the help of witnesses. Five special teams of Delhi Police raided a house in south Delhi's Khirki Extension, which was used by the accused as their hideout.
"The house belongs to a criminal Hari Kishan, who had recently purchased the house in his wife's name and had recently shifted there. A raid on the house led to the recovery of the key of the cash van and some incriminating documents," said the officer.
Police also recovered two broken iron currency chests about 100 metres from the house.
"Residents from Malviya Nagar informed police that a car, matching the description of the accused's vehicle, was moving in the area for the last few days with four men in it," added the officer.
Raids were conducted in nearby Pusp Vihar colony, from where Deepak was arrested with Rs.1.51 crore. On his disclosure, two other co-accused - Mukesh and Tekram - were arrested from their hideouts, police said.
Police also recovered Rs.85.85 lakh from their relatives in the national capital region.