Raj Kwatra was found murdered with throat slit in her flat of Shipra Sun City on September 3.
Domestic help Puspha hatched a conspiracy to murder the elderly woman and sought assistance of her boyfriend Ajay and his friend Anuj in the crime, police said.
Both Ajay and Anuj worked as security guards in the society while the family of Kwatra had hired Pushpa for work on August 18, they said.
The trio murdered Kwatra in her residence on September 3 and escaped with jewellery worth lakhs and Rs 3,000 cash, a senior police officer said.