The police said that the juvenile, who lives in the upscale Sector 51 area, tied her hands and legs to the bed and raped her on Thursday.
The police said the accused murdered Roshan Lal in an apartment in Sector 103 on the night of October 31.
Hearing the commotion, neighbours rushed to the flat and saw the two lying in a pool of blood and the frightened boy standing nearby.
According to the police, victim's brother Sailendra Singh alleged that Abhinav Agrawal, a friend of his brother had visited their house.
The incident occurred on February 23, 2016 in Haryana, when the three accused, Vipin, 20, his brother Nitiesh Kumar, 20, and their friend Monu, 24, raped and killed her.
The complainant said that she was preparing lunch for her son in the morning when the three eunuchs came to her house and demanded money in return for blessings.