The bodies of three generations of the Bhatia family were discovered by a neighbour who grew suspicious when he found their grocery shop shut on Sunday morning.
The police are yet to establish the sequence of the deaths; whether it was a mass suicide or murder-suicide. Handwritten notes found in the apartment in Burari reveal a possible spiritual connection to the deaths, say the police.
All but one of the bodies were hanging from the ceiling, most of them blindfolded, gagged and their hands tied behind the back. The bodies will be cremated in Delhi today.
Those found dead were Narayan Devi (77), her daughter Pratibha (57) and two sons--Bhavnesh (50) and Lalit Bhatia (45).
Bhavnesh's wife Savita (48) and their three children--Meenu (23), Neetu (25) and Dhruv (15) were also found dead, police said, adding Lalit's wife Tina (42) along with their 15-year-old son Shivam was also among the dead.
Pratibha's daughter, Priyanka (33), who was engaged last month and was to be married by the end of this year, was also found hanging.