He was released by the investigating agency on Saturday afternoon. He has been asked to cooperate with the agency in Delhi as and when required for the ongoing probe into the incident, which claimed 12 lives and injured around 20 others near the Red Fort.

He, along with his father Touhid Alam, stays in Ludhiana, sources said.

Acting on a tip-off, the national anti-terror investigating agency had allegedly contacted Touhid in Ludhiana first and collected details of his son. They learnt about Zanishar’s location from his father and then rushed to Dalkhola, sources added.

The NIA’s investigating officials have already arrested four doctors of the controversial university for their alleged involvement in the Delhi blast.

The National Medical Commission, the sole body monitoring medical education across the country, has cancelled the registrations of the four accused doctors, including a woman practitioner, Saheen Sahidi, it is learnt.