Five arrests have been made in the Bihar examination scam, after toppers were unable to answer basic questions about the subjects they 'topped' in.
NDTV reported that two principals of the examination centres were held, a teacher and two employees of the exam board have also been arrested.
The case is being investigated by a Special Task Force following the registration of a police case after the concerned toppers either failed to appear or under-performed in a re-examination.
Earlier, amid mounting pressure with regard to alleged irregularities in the 10+2 exams, Bihar School Examination Board (BSEB) secretary Harihar Nath Jha on Wednesday resigned.
This move comes hours after the board's chairman Lalkeshwar Prasad Singh resigned, following a second showcause notice sent by the education department.
A team of state police and CID visited the BSEB headquarter on Wednesday and perused the results of the intermediate examination.
The team also took away Singh's computer, laptop and smart phone.
The board had first served a notice to the chairman earlier on Saturday over Singh's unilateral decision to set up a judicial probe into the irregularities without the government's nod.
That same day, the department of education set up a committee to investigate the matter as well.
However, Chief Minister Nitish Kumar dissolved both the committees the next day and ordered a criminal investigation into the entire episode.
"It is matter of investigation, not inquiry, to fix accountability and take action against whoever is found guilty," he said.
The Bihar School Examination Board (BSEB) earlier on 4 June cancelled the results of two toppers, including Sourabh Shrestha, of the Intermediate (Science) examinations, after they failed to prove their merit in a re-test.
The board had on 3 June asked Sourabh and his college mate Rahul Kumar, who were among the 13 toppers from the arts and science streams in the Class XII examinations, to take a re-test following a controversy over their merit.
Saurabh Shrestha from the Science stream, who had secured 485 out of 500, was caught on camera failing to answer basic questions.
Ruby Rai, the arts topper, from the same college failed to take the re-test on Friday citing health reasons.
Rai had secured 444 marks out of 500 in the Arts stream. However, on camera she did not even appear to know the number of subjects in her course.
With inputs from ANI