CBI sources said after the case was notified by the Department of Personnel and Training, agency took up the Bihar police FIR to start its investigations.
They said although Bihar government had recommended a CBI probe in the murder last year, it could not be taken up by the agency because of some technical issues.
The agency has recently given its consent to take up the case after which DoPT notified the case to CBI.
He was earlier facing life imprisonment in various carnage cases and was acquitted and released from jail in April last year. The chief of Ranvir Sena, a private militia of upper caste landlords, was allegedly responsible for perpetrating several killings including Laxmanpur Bathe massacre of 61 Dalits in December 1996.
His hand was also suspected in carnages that took place in the districts of Jahanabad, Aurangabad and Nawada in 1990s.