The deceased have been identified as Nagma and her daughter Sofia. Nagma's husband Dildar Ali has been lodged at Tihar Jail for the last two-and-a-half months in a case of robbery.
The incident came to light at around 4:30 AM today when Nagma's father-in-law Arshad Ali raised an alarm. When neighbours rushed to the spot, they found him lying with his hands and legs tied, police said.
He told them that his another son, Kismat had allegedly killed his daughter-in-law and granddaughter in another room.
A case of murder has been registered and since Nagma's marriage to Dildar was less than a year old, the case would be investigated by a sub-divisional magistrate.
Three members of the family, including Ali has been picked up by the police for questioning. Kismat is said to be a drug addict and has been involved in petty crimes in the area, police said.