The CB-CID of the Tamil Nadu Police is investigating the NEET impersonation scam.

Thumb impressions of 4,250 students who were admitted to various medical courses this year in Tamil Nadu should be handed over to investigators, the Madras High Court said on Wednesday, as it asked if the CBI should probe the growing scandal involving proxies taking the National Eligibility cum Entrance Test or NEET.

Adding the CBI as respondent in the case known as the NEET impersonation scam, the court said since the students gamed tests held even outside the state, the fraud could be an all-India phenomenon and many students in various states may have secured admissions through the manner.

"Since the jurisdiction of CB-CID (Crime Branch- Criminal Investigation Department) is only confined to the state government, it would be appropriate for a central agency to investigate into the matter as the medical colleges are located in various parts of our country and the fraud is pan India," the judges said and added the CBI as a respondent.

The state government's lawyer, Additional Advocate General P H Arvind Pandiyan, told the court that six people, including four students, have been arrested in the case. Tamil Nadu has 4,250 of the 38,000 medical seats all over India, however, the admission scandal has surfaced only in the state, he said.

Saying that it has to be verified whether the students who got admission were the same persons who wrote NEET, the court directed the National Testing Agency or NTA to send all details, including thumb impressions, which were taken manually, to the CB-CID and file a compliance report by the next hearing, to find out if any other candidates had got admission by using proxies.

The entire process, right from conduct of exams, counselling and getting admission into medical colleges should be a 'combined process,' making use of thumb impression and facial recognition technology to confirm their identities, the court said.