Seven-year-old Pradyuman Thakur was found with his throat slit in the school washroom last Friday.
The Gurgaon Police detained and questioned Harpal Singh, a gardener at the Ryan International School, who is a key witness in the murder of a class II student, and is likely to make more arrest, a senior SIT officer said on Thursday.
Meanwhile, the Bombay High Court rejected the anticipatory bail pleas of three trustees of the Ryan International Group but granted them interim protection from arrest till Friday to enable them file appeal.
The court also directed the group's CEO Ryan Pinto and his parents Augustine Pinto, the founding chairman, and Grace Pinto, the group's managing director, to submit their passports to the Mumbai police.
In Gurgaon, the Special Investigation Team (SIT) probing the case continued to make efforts to gather more clues as it has decided to file a charge sheet soon. The investigators quizzed the gardener whom they had detained on Wednesday, according to the officer.
Seven-year-old Pradyuman Thakur was found with his throat slit in the school washroom last Friday. Schoolbus conductor Ashok Kumar emerged as the prime suspect and was arrested the same day.
"The SIT does not want to leave out a single piece of evidence which can be important and work as a key breakthrough for us to solve this case. With three days left for submission of charge sheet in court, we have got possible positive leads against the accused Ashok Kumar," the senior SIT officer told PTI.
Some more arrests are likely to be made, he said.
SIT members on Wednesday searched the school for clues while a CBSE panel also inspected the premises to examine loopholes in security arrangements.
Besides Harpal Singh, the SIT has questioned 17 persons including section in-charge Anju Dudeja, suspended acting principal Neerja Batra, former principal Rakhi Verma, bus driver Saurabh Raghav, bus contractor Harkesh Pradhan and eight security guards.
All suspects on the radar, whether it is the suspended school principal, senior management officials or staff members, were being questioned, the officer said.
"The SIT has recovered a total 200 pages of correspondence from the Ryan headquarters in Mumbai, which includes the records of five-page documents on the safety of children, three pages on fire safety equipment, four pages on safety norms and 39 pages on road safety of the school," he said.
Narayan, one of the school guards, gave details as per which the school hired eight guards, who worked in two shifts.
"During the day, only four guards present in the school to secure the safety of 1200 students," Narayan said.
He added that three of the guards were deployed at the gate and the fourth at the entrance of the main building.
The security and safety arrangements at the school have come under the scanner following the brutal murder of the seven- year-old on its campus.
"We are also interrogating the security guards also," the SIT officer said.
Meanwhile, at the Bombay High Court, Justice Ajay Gadkari told the group's CEO Ryan and his parents to submit their passports to the Mumbai police commissioner.
The Pintos had approached the high court seeking transit anticipatory bail apprehending arrest in connection with the murder of the seven-year-old boy in the toilet of the school in Gurgaon.
They had sought pre-arrest bail till they could move the court concerned in Haryana.
"The applications... stand rejected. The interim relief granted to them earlier shall continue till tomorrow 5 pm," the judge said.Barun Thakur, the father of the victim boy, had intervened in the matter, opposing the Pintos' bail pleas.