Police said that the victims were identified as Sunita, 42, and her distantly related brother-in-law Rajesh Kumar, 45. They were attacked with blunt-edged object.
Sunita's body was found lying on a bed in her room while the body of Rajesh was found lying in a pool of blood on the terrace of the building, said a senior police officer.
A tenant of the building found Rajesh's body on the terrace and raised an alarm. Police later arrived and sent the bodies for post-mortem.
Sunita had introduced Rajesh as her distantly related brother-in-law who worked in Haryana Police to her neighbours. He had come to meet her yesterday and his motorcycle was parked outside the building, police said.
Sunita's daughter Jyoti, who had been living with her mother for some weeks due to marital discard, was not present at the time of the incident, said the officer.
Sunita is survived by her two daughters and a 15-year-old son, Sheru, who lived with his elder sister, Sonia who was also married in Haryana. Sunita's husband died ten years ago.