Delhi Police is still searching Navneet Kalra, the mastermind of the oxygen concentrators racket. But meanwhile, a new revelation came out in this case. It is revealed that the business of black marketing of oxygen concentrators was also going on via WhatsApp group. Aaj Tak also has a screenshot of the WhatsApp group, in which Navneet Kalra discussed the demand for an oxygen concentrator on April 26. Watch video.