A bench of Justice G S Sistani and Justice Jayant Nath, however, made it clear to the Delhi Police that they will only subject the suspects to the test after getting their consent.
"Why should anybody, who is related to the case, shy away from helping in the investigation? We do not want to give concession to anyone, whether it is the family members, friends or Najeeb's roommate. Lie-detector test should take place, as every body will have to work on this case.
"We want that something substantial comes out of the effort we all are involved in, before the next date of hearing," it said.
Najeeb has been missing since October 15 after a scuffle at his hostel allegedly with ABVP students the previous night.
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A reward of Rs 10 lakh has been announced by the police on any information about Najeeb, who has remained untraced even after 69 days of the incident.
Gonsalves also submitted that the police have searched
the houses of Najeeb's relatives and distant relatives but did not even bother to look in the rooms of the suspect, who all have left for their homes after the incident.
Mehra opposed the contention and submitted that they would have done so, if it would have been pointed out earlier. He said the agency had issued notice to those nine and they are on their way to Delhi.
On this, the court remarked that the investigation should be done uniformly, whether one is a suspect or not.
"Roommate and these nine boys should have been interrogated at the initial stage only. They should have been subjected to lie-detector test," the bench said and asked the police whether they have called the parents and family members of Najeeb for the test.
"Did you (investigating officer of the case) interrogate Najeeb's brother and his family members in this regard? You should have done this also. As far as we are concerned, we thought the nine suspects were staying at the hostel in the JNU campus. But if you would have told this to us, we would have definitely asked the police to search their rooms in Delhi as well out of Delhi," the court said.
"If they have not done anything, why will they shy away from allowing a search of their hostel rooms or their houses? What is there to hide? They will have to cooperate with the ongoing investigation so that something conclusive comes out."
The court was hearing a habeus corpus plea by Najeeb's mother, Fatima Nafees, seeking to trace out her son who has been missing since the intervening night of October 14-15.
Following the court direction, Mehra today told the court that they have searched the entire JNU campus for two days, but have not been able to find the boy.
The senior standing counsel further submitted that they will go for lie-detector test of the persons concerned.
While deliberating the steps carried out to search the missing student, he informed the court that over 600 police personnel assisted by two squads of sniffer dogs and four squads of mounted police concluded their search of the sprawling JNU campus but could not find any clue.