Police said the crime occurred around noon on Tuesday on the second floor of the '21 National Park' housing society in the Amar Colony area.
Police said investigation into the robbery-cum-murder revealed that deceased Sarita Jain had taken on Roshan as a servant two weeks ago. He allegedly facilitated a friendly entry of four accomplices who held her hostage and her other servant Rajan.
"They tied up Rajan and Sarita. They later strangulated her and decamped with cash and jewellery. The woman's son was away from the house at that time. The police verification of the accused servant was not got done by the family," Deputy Commissioner of Police Romil Baaniya said.
"Prima facie, he is the key conspirator and planned the crime with his accomplices," the officer said.