Designated CBI court judge Chaudhary Birendra Kumar Rai passed the order convicting Rustam Mian after finding him guilty of the charges against him in the murder committed 15 years ago.
Chandrashekhar was shot dead by unidentified armed assailants in Bihar's Siwan district on March 31, 1997 while he was campaigning against criminalization of politics.
The CBI court had on March 2012 sentenced three persons - Dhruv Kumar Jaiswal, Shekh Munna Khan and Iliyas Bari alias Mintu - to life imprisonment and imposed a fine of Rs 40,000 on each after finding them guilty of the murder.
Mian's case was being tried separately by the CBI court.
