52-year-old Chakravarty, who was an Inspector in RAW and was posted as field official in Cabinet Secretariat was found hanging in his house while his wife Jaishri (42), daughter Disha (12) and son Arnab (17) were found dead with multiple head injuries and slit throats.
Investigators probing the case have questioned the family's neighbours, maid and the guard to find that Chakravarty felt left out as his two children took the side of their mother whenever the couple had a quarrel.
Neighbours have revealed that they had often heard the couple quarrelling but nobody from the family spoke about it even though the family is being described as "friendly" by them.
The time of actual occurrence of death will emerge only after the post mortem, which is expected to take place tomorrow in All India Institute of Medical Sciences (AIIMS).
Chakravarty hailed from West Bengal and had no immediate relatives in Delhi. His two married younger sisters lived in other cities, said a police officer.
All the forensic evidences collected from the crime scene have been sent to the Central Forensic Science Laboratory (CFSL), police said.