Police tracked the accused's movement on the Metro. (Representational)
Footage from 300 CCTV cameras, surveillance on a Delhi Metro Smart Card and joint action with Metro staff helped police crack the high-profile murder case of a builder, sources have said.
The body of 77-year-old Ram Kishore Agrawal was found at his home in north Delhi's Civil Lines area last Sunday. His throat had been slit and the body had marks of stab injuries.
Some cardboard boxes containing cash were found missing from the house, police had said, pointing to robbery as a possible motive behind the killing.
Police have arrested two juveniles aged 16-17 years. "The mastermind is a school dropout. One of them worked as a servant at the builder's house. They were well-versed with his daily routine, the topography of the house and the whereabouts of assets," Dependra Pathak, Special CP, Law and Order, Delhi Police, told news agency ANI.
Mr Pathak added that a motorcycle, cash worth Rs 10.37 lakh, gold jewellery and foreign currency were recovered from them. "Their movement was identified and was caught in efforts with DMRC. They made a foolproof plan as they were aware of the victim's house," he said.
One of the arrested accused has said he is from Bihar and claimed that he is a minor.
Police sources said the accused worked as a cleaner at Mr Agrawal's home about one-and-a-half years ago and that he has some other cases against him.
Police sources said that the accused was taken into custody at the Rajiv Chowk Metro station after he was tracked down using CCTV footage.
During the course of the investigation, police found that the accused reached Mr Agrawal's residence the night before the murder and parked a stolen bike outside.
One of the accused walked to the Civil Lines Metro station, took a train to New Delhi station and then to Samaypur Badli. From the Samaypur Badli station, he took an auto-rickshaw to his home.
The next day, he took an auto-rickshaw to Civil Lines, the two allegedly killed the builder and then fled on the bike they had parked there the night before, police sources said.
During the probe, police scanned footage from over 300 CCTV cameras to identify the accused. They were seen wearing masks throughout.
Police then tracked the accused's movement on Metro and alerted officials and security there. Surveillance began on the accused's Metro Smart Card and as soon as he used it this morning, a special staff of Metro security took him into custody.