All nine suspects, who were summoned by the Central Bureau of Investigation (CBI) in the case, also appeared before the court to give their consent for polygraph test on Wednesday.
All the suspects are students of the JNU and a few of them are members of Akhil Bhartiya Vidyarthi Parishad (ABVP).
The Delhi High Court handed over the case to the CBI after Najeeb's mother, Fatima Nafees, approached it following police's failure to trace him.
The CBI registered First Information Report (FIR) in June and started investigation. It is alleged that there was an altercation between Najeeb and the students affiliated to the Akhil Bharatiya Vidyarthi Parishad (ABVP) on October 14, 2016.
On June 29, CBI declared reward of Rs. 10 lakh for information about the whereabouts of Najeeb. (ANI)