The Central Bureau of Investigation (CBI) has registered a criminal case and initiated an investigation in the NEET question paper leak case. Special teams have been formed by the CBI to investigate the matter on top priority. Special CBI teams are being sent to Patna and Godhra where local police cases have been registered. CBI has registered the FIR based on a report from the Bihar Economic Offences Unit (EOU). Sources claim that officials involved in the probe suspect that the question paper was leaked from Oasis School in Jharkhand's Hazaribagh district. According to an EOU source, a question paper with booklet number 6136488 was purportedly shared on the WhatsApp group of the 'examination mafia' in Patna. This booklet was received by the school in Hazaribagh. During the investigation, it was also found that the box in which the booklet reached the school had been tampered with. The CBI is now trying to determine whether the question paper was leaked while it was being moved to the bank, or if it was stolen somewhere mid-route between the bank and the examination center. According to a source, Sanjeev Mukhiya, an employee of Nursarai Udyan College, Nalanda, was the kingpin of the 'paper leak gang'. He has allegedly been conspiring with his associates to leak the NEET exam paper for several months. Before the exam, a professor reportedly sent the paper to Sanjeev Mukhiya on WhatsApp. The paper was then solved by PG medical students from Patna and Ranchi. After solving all the questions, it was sent to Chintu Kumar, a.k.a. Baldev, on his cellphone in the Karayparsurai block in Nalanda district. The Bihar EOU also discovered a list of selected candidates who were given the paper before the exam and were made to memorize the answers. The EOU has so far arrested 13 people in connection with the matter. Besides, many others are being questioned. The Special Investigation Team (SIT) of the EOU has conducted raids in Deoghar, Jharkhand, and arrested six persons, including Chintu Kumar, who is said to be a relative of the kingpin, Sanjeev Mukhiya. According to sources, the EOU has also identified the PG medical students who solved the NEET exam paper. Ten students from medical colleges in Patna and Ranchi are under its scanner. The SIT learned about the role of these PG medical students based on some WhatsApp chats with the accused individuals. The accused allegedly sent the question papers to the students on their mobile phones. Earlier, the CBI registered the FIR on Saturday night and has started the investigation. The Education Ministry summoned Nayyar Hasnain Khan, Additional Director General of Bihar's EOU, to provide information related to the paper leak. On Saturday, Khan met Union Education Minister Dharmendra Pradhan in Delhi and submitted the probe reports to him. Following the recommendation of the Central government, the CBI registered the case on Saturday night. The NEET examination was held on May 5, and its question paper was made available to the 'education mafia' a day earlier, on May 4.