The accused, Sunil, 25, was arrested by a team of the Crime Branch from near Peer Baba Majaar at Sector 22 in Rohini, said Ravindra Yadav, Joint Commissioner of Police (Crime).
A total of ten accused, including two women and a Delhi Police constable, has so far been arrested in the robbery case.
The accused, including Sunil, had gained entry to the house of the victim at Mahavir Nagar in Tilak Nagar area with the help of a woman accused, Ranjeet Kaur, who had claimed to be on a survey exercise, on July 3.
The gand threatened the victim, her mother-in-law and daughter with guns and looted jewellery weighing about 700 gm, Rs 1.32 lakh in cash and property documents, he said.
The robbery was masterminded by Satender who is a distant relative of the family which is in property business, he added.