Bhawani Shankar Pandey, a retired principal of a private school in Bihar's capital Patna, was arrested on May 24 on the charges of selling fake age certificates to crime suspects to enable them get bail on the grounds of being a juvenile, they said.
"Pandey has issued more than 100 fake age certificates between 2011 and 2013 for money, including many to hardcore criminals like some charged with three to four murder cases.
One Makhkhan Gope, accused of committing 30-40 cases of murder, has been issued age certificate from Pandey's school," Patna Senior Superintendent of Police Manu Maharaj told PTI.
Mr Pandey also used to depose in courts to certify his clients as juvenile for which he used to charge hefty amount, the police officer said.
With the help of fake age certificates, these criminals used to easily get bail from courts, the SSP said.
Bittu, a resident of Beur area in Patna and allegedly involved in four-five murder cases, had also filed a bail application on the basis of age certificate. Police were verifying his certificate, he said.
Police zeroed in on Mr Pandey last month after Santosh Kumar Singh, father of an engineering student Saurabh Kumar who was killed in 2015, challenged the age certificate which the accused produced in the court to claim the status of a juvenile, police said, adding that Mr Pandey had allegedly issued the certificate to the accused whose age was being verified.
In another incident, the family of a suspected dowry death victim Suman Kumari alleged that the accused in the case used a fake School Leaving Certificate from Pandey to claim he was not 27 years old, but only 17 when the case was registered in 2015, they said.
Mr Pandey also allegedly issued a fake certificate to Ranjit Kumar, who is accused of killing a marble trader Ramchandra Jha in Patna in September 2016.
Police is investigating whether Mr Pandey sold fake certificates to criminals outside Bihar.
Mr Pandey continued to run his school despite it being de-recognised by the government in 2013, they said.
He is currently on judicial custody.