The accused, identified as Rajesh alias Suraj, who carried a cash reward of Rs 50,000 on his head, was arrested on Wednesday from the Kirari area following a tip-off.
According to police, Rajesh was wanted for the murder of the woman at her residence on January 29, 2014, during a robbery carried out by him and his associate.
Police said that the robbery was planned by Rajesh along with one Raman, who had provided his services as a driver to the family of the victim.
"Her husband left after dropping her to her destination. After some time, as she repeatedly called her husband, the phone was answered by Raman, who kept telling her that her husband Shailesh was busy with his friends," said Joint Commissioner of Police (Crime), Ravindra Yadav.
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On returning home at about 1.30 P.M., Sandhya found her mother lying dead on the floor in a pool of blood and their household articles scattered around and locks of almirahs broken, he said.
Shailesh alleged that Raman and his associate Rajesh had committed the crime after drugging him, police said.
Following his arrest, Rajesh has confessed to the brutal murder of the old woman with his associate Raman. He told police they had first drugged Shailesh in the car itself and then abducted him before taking the keys of his house from him.
The duo had fled in Shailesh's car and later left him tied up in a semi-conscious state at an isolated place behind M2K market.