Maitra died of a suspected drugs overdose, while Rahul, the late Bharatiya Janata Party leader Pramod Mahajan's only son, is recovering at the Apollo hospital.
The Delhi police arrested at least nine Nigerian nationals, suspected to be drug traffickers, after conducting raids at several sites in the capital in a bid to trace the source of procurement of the drugs.
Cocaine found in Rahul's urine sample
The police also visited the Apollo Hospital to question Rahul, who is still in the intensive care unit, but were told by doctors that he was 'unfit' to make a statement.
After interrogating Sahil for over four hours, the police claimed the 21-year-old lad, who has been booked under the Narcotic Drugs and Psychotropic Substances Act for consumption, sale and purchase and sourcing drugs, had admitted to having got drugs for Rahul and Maitra for Thursday night's party.
"He was very much there and he got the drugs for them. That is what he has disclosed," Additional Deputy Commissioner of Police (New Delhi district) Manish Agrawal told reporters in New Delhi after the police questioned Sahil.
Agarwal claimed Sahil got the drugs from the Vasant Vihar area of Delhi, but the police is not aware of the quantity of narcotics he procured.
Sahil, brought to New Delhi from Srinagar after his arrest on Saturday, was produced on Sunday before Metropolitan Magistrate Sanjeev Kumar who remanded him to police custody till June 12. The Delhi police said it wants to take Sahil to Mumbai and Srinagar in connection with the investigation.