The accused, identified as Shubham Bhardwaj, a resident of Jahangirpuri, was involved in the killing along with his friends, they said.
Delhi University student murder: Deputy CM Manish Sisodia meets victim's family, announces Rs 10 lakh ex-gratia
Sisodia said the Delhi government will ensure that the culprits get strict punishment at the earliest by appointing prominent lawyers in the case.
Police sources said that investigation has revealed that the accused is the son of a former MLA from BSP and SP.
The accused threw an iron rod at the boy, which hit him on the head, and out of fear of being identified, he strangled the boy, the official said.
Suraj was found in an unconscious condition in the washroom of the Government Scheduled Caste-Tribe Boys Hostel.
Between 2012 and 2013, the police has filed a couple of reports about the rising religious fundamentalist activities on college campuses.
Angry parents and locals gathered outside the school premises since early morning to express dissatisfaction over the investigation being carried out by the Gurgaon Police.
Haryana Education Minister Rambilas Sharma said that it was the responsibility of the school management to keep students safe inside the school premises, but they failed to do so.
The window panes and other property were damaged, as the angry parents reportedly demanded a CBI probe into the incident.